REESE  LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Deceived  J^<£su~<  ,  i$Q9 • 

• 

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I U LI — U 1? 


•Accession  No. 


3obn  Mile?  &  Sons. 


THE    COFFER-DAM    PROCESS 
FOR   PIERS. 


FOWLER, 


THE 


COFFER-DAM     PROCESS 
FOR     PIERS. 


PRACTICAL  EXAMPLES  FROM 
ACTUAL  WORK. 


CHARLES    EVAN    FOWLER, 

31  ember  American  Society  of  Civil  Engineers , 
Bridge  Engineer. 


"  Much  of  the  success  of  any  one  in  any  kind  of  work,  and  especially  in 
work  subject  to  the  peculiar  difficulties  of  that  we  are  considering,  depends 
upon  the  spirit  in  which  it  is  undertaken.  "-—ARTHUR  MELLEN  WELLINGTON. 


FIRST    EDITION. 
FIRST    THOUSAND. 


NEW   YORK: 

JOHN    WILEY   &    SONS. 

LONDON:    CHAPMAN  &  HALL,  LIMITED. 
1898. 


Copyright,    1898, 

BY 
C.   E.   FOWLER. 

6  2. 


ROBERT    DRUMMOND,  ROBERT^DRUMMOND, 

P.   H.  RANCK°PUB.  CO.,  444  PBARL  STREET, 


Electrotypes. 


NEW  YORK. 


INTRODUCTION. 


THE  greater  part  of  foundation  work  is  of  an  ordinary  character.  And 
while  difficult  foundations  have  been  quite  fully  treated  by  engineering  writers, 
ordinary  ones  have  too  often  been  passed  over  with  mere  mention,  or  treated  in 
such  a  general  way  that  the  information  proves  of  little  value  in  actual  practice. 

Many  valuable  examples  of  work  of  this  character  have  been  described  in 
current  engineering  literature,  and  it  is  hoped  that  by  bringing  them  together 
a  real  service  will  be  rendered  the  profession,  as  well  as  much  valuable  time 
be  saved  for  considering  other  and  equally  important  problems. 

The  history  of  the  coffer-dam  process  would  seem  to  indicate  that  engineers 
of  nearly  a  century  ago  gave  more  consideration  to  the  smaller  problems  than 
the  engineer  of  to-day,  who  has  apparently  passed  to  the  consideration  of  the 
larger  and  of  course  more  interesting  ones. 

That  this  is  deplorable,  is  proven  by  the  many  cases  where  money  has  been 
wasted  in  the  after  effort  to  make  good  the  mistakes  that  have  become  appar- 
ent where  cheap  construction  of  coffer-dams  has  been  resorted  to.  The  saving 
in  original  cost,  as  between  an  indefensible  method  and  a  defensible  one,  is 
often  so  small  as  to  seem  absurd  when  it  has  become  necessary  to  make  large 
expenditures  to  rectify  the  errors. 

Errors  of  judgment  are  more  easily  excusable  with  regard  to  foundations 
than  with  any  other  class  of  construction,  but  where  definite  limits  can  be  set, 
economy  will  result  by  keeping  as  closely  as  possible  within  them. 

Reference  is  made  in  the  following  pages  to  the  splendid  construction  of 
foundations  by  the  Romans,  where  they  could  be  built  outside  the  water. 
The  Pont  du  Gard,  illustrated  in  the  frontispiece,  is  the  most  notable  example 
of  this  extant.  It  is  interesting  also  as  indicating  their  knowledge  of  the  better 
form  of  piers  and  methods  of  arch  construction. 

Although  constructed  during  the  reign  of  the  Emperor  Augustus,  at  the 
beginning  of  the  Christian  era,  it  is  in  a  remarkable  state  of  preservation,  aside 
from  repairs  that  have  been  made  from  time  to  time. 

Probably  the  earliest  recorded  examples  of  the  use  of  coffer-dams  which 
give  details  of  construction  are  those  constructed  under  the  engineers  of  the 
Fonts  et  Chaussees. 


IV  IN  TROD  UCTION. 

Those  built  under  Perronet  at  the  bridge  of  Orleans  were  large  and  exten- 
sive, and  references  made  to  the  pile  drivers  and  the  pumps  used  on  the  work, 
serve  to  illustrate  the  great  amount  of  attention  paid  to  planning  the  details  of 
construction. 

The  same  engineer  completed  the  piers  of  the  bridge  at  Mantes,  where  the 
coffer-dams  were  constructed  to  enclose  both  the  abutment -and  the  nearest 
pier  within  one  dam,  making  the  dimensions  about  150  feet  by  200  feet  in  the 
extreme! 

Hardly  less  notable  were  the  coffer-dams  at  Neuilly,  where  the  interiors 
were  so  large,  that  the  excavation  did  not  approach  near  the  inside  wall  of  the 
dam. 

All  of  these  were  constructed  prior  to  the  year  1775,  and  the  details  as 
shown  in  the  elaborate  drawings  are  of  much  interest  to  the  engineer  engaged 
on  similar  works. 

The  coffer-dams  constructed  about  1825  by  Rennie  on  the  new  London 
bridge  were  the  prototypes  of  those  used  at  Buda-Pesth,  but  were  elliptical  in 
form.  They  were  designed  with  as  much  care,  apparently,  as  any  other  feature 
of  the  bridge,  and  from  the  fact  that  the  water  was  pumped  to  twenty-nine  feet 
below  low  water  and  the  work  found  tight,  the  details  must  have  been  very  care- 
fully executed. 

However  great  the  amount  of  care  bestowed,  there  will  be  cases  undoubtedly 
where  the  difficulties  cannot  be  foreseen,  and  it  will  become  necessary  to  adopt 
some  of  the  many  expedients  cited  to  overcome  them  ;  or  they  might  better  be 
employed  from  the  start,  where  any  suspicion  is  had  that  trouble  may  ensue. 

The  question  as  to  whether  it  will  be  best  to  use  a  crib  or  a  sheet-pile  cof- 
fer-dam will  most  always  be  decided  by  the  character  of  the  bottom,  the  loca- 
tion, and  the  character  of  the  foundation  to  be  built.  It  is  advisable,  whichever 
type  is  selected,  to  make  the  size  large  enough,  so  that  the  excavation  may  be 
completed  without  approaching  too  close  to  the  inside  wall  of  the  dam,  and  so 
that  plenty  of  room  may  be  had  for  the  laying  of  the  foundation  courses. 

The  unit  stress  adopted  for  timber  construction  is  believed  to  be  as  large  as 
will  give  good  results  in  the  majority  of  cases,  both  on  account  of  the  possibil- 
ity of  the  construction  having  to  undergo  more  severe  usage  than  is  expected, 
and  on  account  of  the  grade  of  timber  which  is  most  often  made  use  of  for  tem- 
porary works. 

Where  it  is  permissible  from  the  standpoint  of  true  economy,  it  is  believed 
that  steel  construction  will  commend  itself  for  use.  In  most  localities  it  will 
not  be  long  until  metal  construction  will  be  found  cheaper  than  timber  for  build- 
ing coffer-dams,  and  in  many  places  this  is  already  true. 

A  great  mistake  is  made,  in  nearly  nine  cases  out  of  ten,  by  trying  to  use  old 
machinery,  such  as  hoisting  engines,  pumps,  and  the  like,  which  are  ill  adapted  to 
the  purposes  tor  which  they  are  intended,  on  account  of  lack  of  capacity  and 
only  too  often  on  account  of  having  outgrown  their  usefulness. 


IN  TROD  UC  TION.  V 

The  engineer  would  avoid  many  unpleasant  situations  by  demanding  that  a 
proper  outfit  be  provided,  and  in  the  end  gain  the  thanks  of  the  contractor  for 
increased  profits. 

Extended  acquaintance  with  Portland  cement  is  increasing  the  use  of  con- 
crete in  construction,  and  this  is  a  great  gain  for  the  engineer,  as  it  is  not  only 
superior  to  much  stone  that  is  used,  but  is  better  adapted  to  use  in  difficult 
situations.  It  also  lends  itself  more  readily  to  use  for  ornamental  details  in  pier 
construction.  That  truly  ornamental  piers  are  not,  however,  those  with  need- 
less and  frivolous  details,  has  been  clearly  set  forth  in  the  last  article.  Sim- 
plicity and  beauty  are  near  relatives. 

The  best  locations  cannot  always  be  chosen  for  piers,  but  careful  examina- 
tion will  often  be  the  means  by  which  bad  locations  may  be  avoided. 

The  methods  for  determining  the  economic  division  of  a  given  crossing  of  a 
river,  have  not  come  into  general  use,  probably  on  account  of  lack  of  easy  ap- 
plication. The  method  given  is  an  accurate  one  and  very  simple  to  use,  es- 
pecially if  the  results  are  tabulated  for  a  given  loading. 


TABLE  OF  CONTENTS. 


ARTICLE    I. 

HI  STL  1RICA  L    DK I  'EL  O/>MEN  T. 

PAGE 

Relation  of  Foundation  to  Bridge  Design. — Roman  and  Other  Ancient  Founda- 
tions.—  Bridge  at  Shuster,  Persia. — Roman  Arch  at  Trezzo. —  Four  Ancient 
Methods  for  Foundations. — Method  of  Open  Caissons. — Method  with  Piles  and 
Concrete  Capping. — Method  of  Encaissement.  —  Method  of  Coffer-dams. — 
Caesar's  Bridge  over  the  Rhine.  —  Pneumatic  Caissons  and  Coffer-dams  appli- 
cable to  Different  Cases. — Origin  of  Coffer-dams  and  Primitive  Types. — The 
Hutcheson  Bridge  at  Glasgow.  —  Robert  Stevenson's  Specifications  for  Coffer- 
dams on  Hutcheson  Bridge. — Old  Directions  for  Triple-puddle  Coffer-dam  in 
Forty  Feet  ( !)  of  Tide-water. — W.  Tierney  Clark's  Account  of  the  Great  Coffer- 
dams for  the  Buda-Pesth  Suspension  Bridge.  —  Character  of  Puddle  used. — Class 
of  Work  to  which  Coffer-dams  should  be  applied. — Value  of  Actual  Examples..  i 


ARTICLE    II. 

CONSTRUCTION  AND  PRACTICE.     CAY/.1   COFFER-DAMS. 

Definition  of  Coffer-dam. — Simple  Clay  Bank. — Drag  Scraper  for  removing  Soft 
Bottom.  —  Excavating  Spoon.  —  Larger  Dredges  mentioned.  —  Crib  and  Embank- 
ment used  on  Chanoine  Dams  on  Great  Kanawah  River. — Improvised  Na- 
smyth  Sheet-pile  Hammer. — Failure  on  Ohio  River  because  of  Porous  Bottom. 
—Crib  Coffer-dam  with  Puddle  Chamber,  C.,  B.  &  Q.  R.  R.— Cribs  without 
Puddle  Chambers,  Can.  Pac.  Ry.— Cribs  of  Old  Plank,  Santa  Fe  Ry.— Crib  for 
Arkansas  River,  St.  L.  and  S.  F.  Ry.— Sheet  Piles  used  on  Santa  Fe.  — Sheet 
Piles  used  on  Union  Pacific  Ry. — Coffer-dam  on  Grillage,  Union  Pacific  Ry. — 
Circular  Coffer-dam  of  Staves  at  Fort  Madison,  la. — Circular  Coffer-dam 
pailure  at  Walnut  St.,  Phila.  —  Probable  Cause  of  Failure. — Form  of  Construc- 
tion to  adopt. — Use  of  Puddle. — Cutwaters. — True  Economy  of  Construction.  .  13 

ARTICLE    III. 

CONSTRUCTION  AND   PRACTICE.     CRIBS  AND   CANT  AS. 

Stopping  Leaks. — Canvas  Bulkhead  at  Keokuk,  Iowa. — Canvas  Funnel  for  Springs. 
— Anchoring  Cribs  and  Crib  Coffer-dam  at  St.  Louis. — Timber  Casings  cov- 

vii 


Viil  TABLE    OF  CONTENTS. 

PAGE 

ered  with  Canvas,  Melbourne. — Strength  of  Water-soaked  Timber.  —  Polygonal 
Crib  for  Harlem  Ship  Canal  Pivot  Pier. — Polygonal  Crib  for  Arthur  Kill 
Bridge. — Octagonal  Crib,  Coteau  Bridge 28 

ARTICLE    IV. 

PILE    DRIl'ING  AND   SHEET  PILES. 

Historical  Forms  of  Pile  Drivers. — Simple  Sheet-pile  Driver. — Large  Pile-driving 
Derricks. — Machinery  for  Pile  Driving. — Cost  of  Outfits. — Nasmyth  Hammers 
of  Various  Types.— Loads  on  Guide  and  Foundation  Piles.  —  Pulling  Piles  and 
sawing  off  under  Water. — Forms  of  Sheet  Piles. — Wakefield  Sheet  Piling. — 
Shoes  for  Sheet  Piling. 40 


ARTICLE    V. 

CONSTRUCTION   WITH   SHEET  PILES, 

Water  and  Puddle  Pressure. — Calculation  of  Sheet  Piling. — Size  of  Wales  and 
Struts. — Width  of  Puddle  Chambers. — Guide  Piles  and  Guides. — Ann  Arbor 
Sheet-pile  and  Puddle  Coffer-dam,  M.  C.  Ry. — Failure  with  Sheet  Piles  at 
Arthur  Kill  Bridge. — Successful  Method  adopted. — Sewer  Coffer-dam  for 
Boston  Sewerage  System. — Wakefield  Sheet  Piling. — Harper's  Ferry  Coffer- 
dam.—Momence,  111.,  Coffer-dam,  C.  &  E.  I.  Ry.— Sheet  Piling  for  Charles- 
town  Bridge  Piers. — Polygonal  Sheet-pile  Reservoir  Coffer-dam  at  Fort 
Monroe,  Va 54 

ARTICLE    VI. 

CONSTRUCTION   WITH  SHEET  PILES. 

Combinations  of  Various  Forms  of  Sheet  Piles. — Sheet-pile  and  Puddle  Coffer- 
dam, Walnut  Street  Bridge,  Chattanooga. — Framing  of  Cumberland,  Md., 
Coffer-dam. — Sandy  Lake  Coffer-dam  and  Pile-driving  Plant. — Driving  Sheet 
Piles  with  Water  Jet.  —  Use  of  Sheet  Piling  on  Foundations  of  Main  Street 
Bridge,  Little  Rock. — Concrete  Piers  at  Little  Rock. — Removal  of  Old  Pier  at 
Stettin,  Germany. — Removal  and  Repair  of  Pier  in  Coosa  River,  Alabama. — • 
Floating  Coffer-dam  for  P.  &  R.  R.  R.  Bridge  over  the  Schuylkill. — Use  of  Six- 
inch  Sheet  Piles  at  St.  Helier,  Jersey. — Stock  Rammer  to  stop  Leaks. — Single- 
pile  Coffer-dams,  Putney  Bridge. — Twelve-inch  Sheet  Piling,  Victoria  Docks. — 
Tongue  and  Groove  Sheet  Piling,  Topeka,  Kansas.  —  Use  of  Dredging  Pump 
at  Topeka - 66 

ARTICLE    VII. 

METAL    CONSTRUCTION. 

Thin  Steel  Shells.  — Hawkesbury  Oblong  Metal  Piers.— Vertical  and  Inclined  Cut- 
ting Edges. — Water-tight  Construction. — Pivot  Pier  of  Clustered  Cylinders. — 


TABLE   OF  CONTENTS.  ix 

PAGE 

Double-cylinder  Pier. — Russian  Ornamental  Cylinder  Piers. — Lighthouse 
Cylinders. — Calculation  of  Thin  Metal  Cylinders. — Forth  Bridge  Metal  Coffer- 
dams.—  Forth  Bridge  Circular  Granite  Piers. — Combined  Metal  Coffer-dam  and 
Pier  Base. — Metal  Sheet  Piles 80 


ARTICLE    VIII. 

PUMPING  AND  DREDGING. 

Amount  of  Pumping  indicates  Success.  —  Bascule  for  Pumping. — Chapelet  for 
Pumping.  —  Bucket  Wheel  used  at  Neuilly.  —  BQX  Lift  Pump. — Metal  Lift  Pump. 
— Diaphragm  Pump. — Steam  Siphons. — Van  Duzen  Jet. — Lansdell  Siphon. — 
Pulsometer  Steam  Pump. —  Maslin  Automatic  Vacuum  Pump. —  Comparative 
Efficiency  of  Centrifugal  and  Reciprocating  Pumps. — Tests  of  Centrifugal 
Pumps. — Direct-Connected  Engine  and  Centrifugal  Pumps. — Use  of  Electric 
Power. — Suction-pipe  Details. — Type  and  Capacity  of  Pump. — Methods  of 
Priming. —  Double-suction  Pumps.  — Dredging  Pumps.— Clam  shell  and  Grapple 
Dredges. — Sand  Diggers  and.  Elevator  Dredges. — Dipper  Dredges. — Cost  of 
Dredging 9: 


ARTICLE    IX. 

THE  FOUND  A  TION. 

Character  of  Foundation. ^-Kind  of  Bottom. — Soft  Bottom. — Pile  Foundation. — 
Soft  Material  overlying  Hard  Bottom. — Clean  Smooth  Rock. — Sloping  Rock. 
—  Rough  Rock. — Concrete  Levelling  Course. — Concreting  under  Water. — Mono- 
lithic Concrete  Piers. — Concrete  Piers  at  Red  River. — Monolithic  Concrete  on 
Illinois  and  Mississippi  Canal. — Requirements  for  Good  Concrete.  —  Compo- 
sition of  Concrete.— Contractor's  Plant. — Cableways 106 

ARTICLE   X. 

LOCATION  AND   DESIGN   OF  PIERS. 

Location  at  Fixed  Site. — Location  at  New  Site. — Government  Requirements. — 
Examination  of  Site. — Test-boring  Apparatus. — Mississippi  River  Commission 
Boring  Device. — Economical  Length  of  Spans. — Ottewell's  Formula  for  Eco- 
nomic Span. — Morison's  Design  for  Piers. — Omaha  Union  Pacific  Piers. — Rus- 
sian Piers. — Obstruction  caused  by  Piers.  —  Cresy's  Experiments  on  the 
Obstruction  caused  by  Piers. — Correlation  of  Theoretical  Form  and  Archi- 
tectural Design 120 


TABLE    OF    COFFER-DAMS.- 


,   & 

X       £ 

River  and  Location. 

C-en,.       *£' 

Character  of  Bottom. 

i      5 

2       6 

3      8 
4      9 
5    U 
6    15 

7    17 

S    18 
9    18 
10    18 

II      20 

12     2O 
I3     20 
14     20 
15     20 
I  (  )     2O 
17     20 
IS     24 
I9     30 
20     72 

21    33 

22     36 

23    38 
24    39 
25    59 
2t>    60 
27    60 
28    62 
29    62 
30    63 
3i    (>3 
32    64 
33    66 
34    67 
35    67 
36    70 
37    72 
3S;  74 
39    74 
40177 
-41    77 
42    77 
43    78 
44|86 

River  200  feet  wide    Ohio  

None.              12'  -f 
Slight.              9'  + 
Tide.               40' 
Swift.              54'  ± 
Swift.             34'  - 
Moderate.     20'  -f- 
Moderate.       6'  + 
Swift.             20'  -i 
Swift.             21'  - 
None.              15'  -)- 
Moderate.       7'  -j- 
Moderate.       6'  + 
Moderate.       6'  -+- 
Moderate.       7'  -j- 
Moderate.       6'  -j- 
Moderate.       6' 
Swift.              19' 
Moderate.    Deep. 
None.              12'  -f- 
Swift.          ;   22' 
Swift.             15' 
Moderate.     25' 
Tide.               28' 
Moderate.  !   28' 
Moderate.       6'  -f- 
Tide.               30'  - 
Tide.               10' 
Moderate.       7' 
Moderate.       6'  -+- 
Swift.               6'  + 
Tide.                 6|  + 
None.             20' 
Swift. 
Moderate.     10'  -(- 
Swift.                8'  -f 
Moderate.       6'  -\- 
Moderate.     25'  -j- 
Moderate      10'  -j- 
Swift.               8'  + 
Tide.               13'  + 
Moderate.  Deep. 
Tide.               35' 
Swift.               6'  + 
Tide.               15'  + 

Cemented  gravel. 
Gravel,  sand,  mud. 
Sand  &  gravel  over  clay. 
Gravel  over  clay. 
Gravel  over  hardpan. 
Gravel. 
Soft. 
Rock. 
Rock. 
Sand. 
Gravel  over  rock. 
Soft. 
Sandy. 
Gravel  over  soapstone. 
Rock. 
Soft. 
Soft. 
Mud  over  rock. 
Rock. 
Rock. 
Rock. 
Rock. 
Clay  over  rock. 
Rock. 
Gravel. 
Mud  and  clay. 
Sand  and  gravel. 
Sand  and  mud. 
Rock. 
Rock. 
Soft. 
Soft. 
Gravel  over  rock. 
Sand  over  hardpan. 
Sand. 
Sand. 
Clay. 
Gravel  over  rock. 
Rock. 
Earth  over  rock. 
Mud. 
Rock. 
Sand. 
Rock. 

Danube  at  Bud  a  Pesth              .    •  - 

Western  part  United  States  

Western  part  United  States  

Western  part  United  States  

Western  part  United  States  

Payette  and  Weiser,  Union  Pacific. 
Mississippi    Fort  Madison  

Schuylkill  near  Philadelphia,  Pa... 
U    S    Canal    Keokuk 

Arthur  Kill   Bridge 

Coteau  Bridge    C    Pac    Ry 

Ann  Arbor,  Mich.,  M.  C.  Ry  
Arthur  Kill  Bridge  

Boston  Harbor    sewer  

Illinois  River    La  Grange  

Kankakee  at  Alomence  

Potomac  at  Harper's  Ferry  
C  harlestown  Bridge    Boston  

Cumberland    Md 

Mississippi    Sandy  Lake 

Arkansas    Little  Rock     .  . 

Parnitz,  Stettin,  Germany  
Coosa,  Gadsden,   Ala  
Schuylkill    P    &  R    R    R 

St.  Helier   Bridge,  Jersey,  Eng.  .  .  . 
Thames  at  Putney 

Victoria  (B    C  )  Docks 

Kaw  at  Topeka  

SYNOPSIS    OF    EXAMPLES. 


Form  of  Construction. 

Inside 
•  Dimensions. 

Kind  of  Puddle.                  'Vuddle*8 

Remarks. 

i  '  £ 

Earth  bank. 

TO'  X  60'? 

Clay  and  gravel.                   5'  4- 

No  leaks. 

5 

Sheet  piles. 

20'   X   58'? 

Clay.                                         3' 

6        2 

Sheet  piles. 

Large. 

Clay,  sand  &.  gravel.           3~6' 

Typical. 

8      3 

Sheet  piles. 

72'  X  136'  + 

Clay  and  gravel.          •         2-5' 

Difficult.             9      4 

Earth  bank. 

90'  X  33°' 

Clay  and  gravel.                 19'  4~ 

J4      5 

Earth  bank.? 

200'  X  600' 

Clay  and  gravel. 

Failed.              15      6 

Crib. 

Medium. 

Clay.                                           3'  4- 

17       7 

Crib,  single. 

24'  X  43' 

Concrete  inside. 

18      3 

Crib,  single. 

1  6'  X  34' 

Concrete  inside. 

IS          Q 

Crib,  single. 

17'  X  43' 

Clay  outside. 

Special.             18    10 

Crib,  single. 

Medium. 

Clay  outside. 

20      II 

Sheet  piles. 

Medium. 

Typical.            20     12 

Sheet  piles. 

Medium. 

Clay  outside. 

20    13 

Sheet  piles. 

Medium. 

Clay  outside. 

20    14 

Sheet  piles. 

Medium, 

Clay.                                 Equal  depth. 

20      15 

Box  or  crib. 

12'  X  36' 

None. 

On  grillage.  '<  20    16 

Staves. 

36'  diam. 

None. 

On  grillage.    20    17 

Sheet  piles. 

So'  diam. 

None. 

Failed.              24    18 

Canvas  on  plank. 

So'  long. 

Rotten  manure. 

Bulkhead.       30    19 

Crib,  double.              28'  X  64' 

Clay. 

3'o" 

Canvas  used   32    20 

Box  and  canvas. 

Square. 

Clay  outside. 

Movable.          33    21 

Polygon  crib.            [47'  diam. 

Clay. 

4'  6" 

36      22 

Polygon  crib. 

44'  diam. 

Clay  and  gravel.                   5'  o" 

38  23 

Crib,  single.              i  34'  diam. 

Concrete  inside. 

39    24 

Sheet  piles.                  13'  X  44' 

Clay  and  gravel.                   2'  3" 

59  1  25 

Sheet  piles. 

Large. 

None. 

Two  trials. 

60  j  26 

Sheet  piles. 

12'  wide. 

Clay.                                        6'  to  8' 

60    27 

Sheet  piles. 

Medium. 

None. 

62 

28 

Sheet  piles. 

Medium. 

Gravel. 

Two  trials. 

62 

29 

Sheet  piles. 

Medium. 

Gravelly  clay. 

63 

Sheet  piles. 

18'  6"  X  119' 

Concrete  inside. 

63 

3i 

Sheet  piles. 

44'  diam. 

Sand  and  concrete.              7'  -f- 

64 

32 

Sheet  piles. 

Large. 

Clay.                                           ()'  o" 

66 

33 

Sheet  piles. 

15'  x  50' 

None. 

67 

34 

Sheet  piles. 

829'  long. 

Clay. 

S'  ± 

67 

35 

Sheet  piles. 

1  6'  X  38' 

Earth  outside. 

/o 

36 

Sheet  piles. 

23'  X  55'  ± 

Clay. 

2'  to  4' 

Removal. 

72 

37 

Sheet  piles. 

28'  X  28'  ± 

Clay. 

12'  -4- 

Removal. 

74 

38 

Sheet  piles. 

16'  X  42' 

Clay  and  gravel. 

8'  4- 

Movable. 

74 

39 

Sheet  piles. 

Medium. 

Clay  outside. 

77 

40 

Sheet  piles. 

Medium. 

None. 

77 

41 

Sheet  piles. 

500'  long. 

Clay. 

2-7' 

77 

42 

Sheet  piles. 

18'  X  55' 

Clay  outside. 

78 

43 

Metal. 

60'  diam. 

Concrete  seal. 

86 

44 

LIST  OF  ILLUSTRATIONS. 


NUMBER  PAGE 

The  Pont  du  Gard,  Mimes,  France Frontispiece. 

1.  Bridge  at  Shuster,  Persia,  over  the  River  Karun 2 

2.  Bridge  over  the  Adda  at  Trezzo    Milanese 3 

3.  Caesar's  Bridge  over  the  Rhine 4 

4.  A  Primitive  Solution.      (Earth-bank  Coffet -dam .) 6 

5.  Coffer-dam  in  Tide- water.      (Sheet  Piles  and  Puddle.} 8 

6.  Buda-Pesth  Suspension    Bridge.  (Puddle  Coffer-dam.} 9 

7.  Buda-Pesth  Suspension  Bridge,  Plan  of  Coffer-dam  No.  3 n 

8.  Scraper  Dredge.     (For  Drag  Dredging,  C.  &  M.  V.  Ry.) 14 

9.  Coffer-dam  at  Dam  No.  IT,  Gt.  Kanawah  River.    (Earth  and  Crib.} 15 

TO.    Crib  Coffer-dam,  C.,  B.  &  Q.  R.  R.       ( With  Puddle  Chamber.} 16 

11.  St.  Lawrence  River  Bridge,  C.  P.  Ry.      (Crib  and  Coffer-dam] 17 

12.  Arnprior  Bridge,  C.  P.  Ry.      (Crib  and  Coffer-dam} 18,  19 

13.  Crib  Coffer-dam,  A.,  T.  &  S.  F.  Ry.      (A'o  Puddle  Chamber.} 21 

14.  Coffer-dam  on  Grillage,    Payette  and  Weiser  Rivers,  U.  P 22,  23 

15.  Coffer-dam  on  Grillage,   Fort  Madison  Bridge,  A.,  T.  &  S.  F.  Ry 24 

16.  A  Crib  Coffer-dam  after  a  Flood.      (Showing  Plant.} 25 

17.  Apparatus  used  to  force  Clay  into  Crevice  of  Rock.     (Leak.} 29 

18.  Details  of  Canvas  and  Plank  Btilkhead,  Keokuk,  la 31 

19.  Inside  View  of  Bulkhead,  Lock  pumped  Dry,  Keokuk,  la 34 

20.  Canvas  Funnel  for  closing  Leaks.      (Springs.) 35 

21.  Cribs  for  anchoring  St.  Louis  Coffer-dam.      (Crib  and  Puddle.} 36 

22.  Polygonal  (Crib}  Coffer-dam.      Harlem  Ship  Canal  Bridge 38 

23     Details  Coffer-dam,  Arthur  Kill  Bridge.       (Crib  and  Puddle.) 37 

24.  Coffer  dam  for  Pivot  Pier,  Coteau  Bridge.     (Crib.} 38 

25.  Perronet's  Pile  Driver.     (Historical;   Man  Power.) 41 

26.  Perronet's  Bull-wheel  Pile  Driver.     (Historical;   Horse  .Power.) 41 

27.  Sheet-pile  Driver.     (Hand-power  Derrick.) 41 

28.  Pile-driver  Derrick  for  Use  on  a  Scow 42 

29.  Lidgerwood  Pile-driving    Derrick 43 

30.  Hammer  with  Nippers.     (For  Horse  Power.) 43 

31.  Pile-driving  Scow,  New  York  State  Canals.     (Steam.) 44 

32.  Warrington-Nasmyth  Steam  Pile  Hammer 45 

33.  Warrington-Nasmyth  Hammer,  Fair  Haven  Bridge 46 

34.  Cram-Nasmyth  Steam  Pile  Hammer 47 

35.  Machine  for  sawing  off  Piles  under  Water 48 

36.  Pile-pulling  Lever.     (Hand  Power.) •' 49 

37.  Pile-pulling  Scow.     New  York  State  Canals.     (Steam.) 50 

xiii 


XIV  LIST   OF  ILLUSTRATIONS. 


38.  Sheet  Piles  and  Sheet-pile  Details 51 

39.  Charlestown    Bridge.      Driving  Wakefield  Sluet  Piling 52 

40.  Arrangement  and  Diagrams  of  Sizes  for  Sheet-pile  Coffer-dam  x 55 

41.  Sheet-pile  Guides  and  Clamps 57 

42.  Coffer-dam  for  Ann  Arbor  Bridge,  M.  C.  Ry.     (Sheet  Piles  and  Puddle.) 58 

43.  Sewer  Coffer-dam,  Boston  Sewerage  System.     (Sheet  Piles  and  Puddle.} 59 

44.  Wakefield  Sheet  Piling.      (Details. ) Ci 

45.  Type  of  Momence  and  Harper's  Ferry  Coffer-dams.     (Sheet  Piling.) 62 

46.  Coffer-dam  on  Charlestown  Bridge.     (Sheet  Piling.} 03 

47.  Resevoir  Coffer-dam,   Fort  Monroe,  Va.     (Sheet  Piling.) 65 

48.  Compound  Sheet  Pile 67 

49.  Chattanooga  Bridge,  Bed-rock  Pier  No.  3 68 

50.  Framework  of  Coffer-dam,  Cumberland,  Md.       (Sheet  Piling} 69 

51.  Sandy  Lake  Coffer-dam.      (Sh^'t  Piling.} 7o 

52.  Coffer-dam  and  Concrete  Pier,  Little  Rock,  Ark.     (Sheet  Piling 71 

53.  Removal  of  Masonry  Pier  at  Stettin,  Germany.     (Sheet Piling.} 73 

54.  Coosa  River  Coffer-dam.     (Sheet  Piling.} 75 

55.  Stock  Rammer.     (For  packing  Clay  to  stop  Leaks.) 77 

56.  Topeka  Bridge  Coffer-dam.     (Sheet  Piling.} 78 

57.  Havvkesbury  Bridge,  Caisson  No.  6.      (Metal  Shell.') Si 

58.  Group  of  Cylinders  for  Pivot  Pier.     (Metal  Shells.} 82 

59.  Pier  of  Two  Cylinders,  Victoria  Bridge.    (Metal  Shells.} 83 

60.  Circular  Saw  for  cutting  off  piles  under  Water 84 

61.  Cylinder-pier  Bridge,  Riga-Orel  R.  R.,  Russia.     (Metal  Shells.) 85 

62.  Cylinder  Piers,  with  Diaphragm.     (Metal  Shells.} 86 

63.  Circular  Granite  Pier,   Forth  Bridge 87 

64.  Forth  Bridge.      (Metal  Coffer-dam } 88 

65.  Forth  Bridge.     (Circular  Granite  Pier  and  Metal  Coffer-dam} 90 

66.  Old  Bascule  Pump.     (Hand  Power.) 93 

67.  Old  Chapelet,  Side  Eelevation.     (Water-power  Pump.) 94 

68.  Old  Chapelet,  End  Elevation.    (Water-power  Pump.) 94 

69.  Hand  Pump,  Soldered  Joints • 95 

70.  Hand  Pump,  Screw  Joints 95 

71.  Diaphragm  Pump.     (Hand  Power.) 95 

72.  Van  Duzen  Jet  Pump.       (Steam  Power.) 96 

73.  Lansdell's  Siphon  Pump.     (Steam  Power.) 96 

74.  Pulsometer  Steam  Pump 97 

75.  Section  of  Pulsometer 97 

76.  Centrifugal  Pump,  directly  connected  to  Engine 98 

77.  Suction  Details  for  Pumps ; 99 

78.  Centrifugal  Pump,  Double  Suction 100 

79.  Dredging  Pump 100 

80.  Dredging-pump  Piston 101 

81.  Lancaster  Grapple.     (Derrick  Dredge.) 102 

82.  Sand  Digger.    (Light  Elevator  Dredge. ) 103 

83.  Osgood  Dipper  Dredge,  New  York  State  Canals IO^ 

84.  Osgood  Dipper  Dredge,  Details,  New  York  State  Canals Io^ 

85.  Metal  Tube  for  Concreting Io-. 

86.  Metal  Bucket  for  Concreting TOS 


LIST   OF  ILLUSTRATIONS.  XV 


87.  Concrete  Piers.  Red  River  Bridge 109 

88.  Concrete  Forms,   Red  River  Bridge no 

89.  Concrete  Forms,   Illinois  and  Michigan  Canal in 

90.  Stone  Crusher  and  Concrete  Mixer,   I.  and  M.  Canal 112 

91.  Double-drum  Guy  Derrick,  Am.  Hoist  &  Derrick  Co 113 

92.  Single-drum  Horse  Power,   Con.  Plant  Mfg.  Co .' 114 

93.  Double-drum  Hoist  Engine,  Lidgerwood  Mfg.  Co 114 

94.  Crocker-Wheeler  Electric  Hoist 115 

95.  Lidgerwood  Cableway  Carriage  and  Skip 1 16 

96.  Lidgerwood  Cableway  at  Coosa  Dam.     (Span  1012  Feet) n3 

97.  Hand  Drill  and  Swab 121 

98.  Steam-power  Well  Driller 122 

99.  Test-boring  Apparatus,    Mississippi  River  Commission 123 

100.  Clamp  and  Maul.     (Test  Boring.) 124 

101.  Pier  of  Omaha  Bridge,  Union  Pacific  System 126 

102.  Russian  Pier,   Russian  State  Railways 127 

103.  Cresy's  Experiments  on  the  Form  of  Piers. 128 

104.  Cresy's  Experiments  on  the  Form  of  Piers 130 


ARTICLE   I.     NTT  = 

THE    COFFER-DAM    PROCESS    FORMERS. 

~~  HISTORICAL  DEVELOPMENT. 


HE  continued  increase  in  the  weight  of  our  bridge  super- 
structures and  of  the  loads  they  have  to  carry  has  led  to 
increased  care,  to  a  very  gratifying  degree,  in  the  prep- 
aration of  the  foundations  for  bridge  piers  and  abutments. 
An  old  authority  very  truly  states  "The  most  refined  elegance  of  taste 
as  applied  in  the  architectural  embellishment  of  the  structure;  the  most 
scientific  arrangement  of  the  spans  and  disposition  generally  of  the  superior 
parts  of  the  work;  and  the  most  judicious  and  workmanlike  selection  and 
subsequent  combination  of  the  whole  materials  composing  the  edifice,  are 
evidently  secondary  to  the  grand  object  of  producing  certain  firm  and  solid 
bases  whereon  to  carry  up  to  any  required  height  the  various  pedestals  of 
support  for  the  spans  of  the  bridge." 

There  is  every  reason  to  believe,  from  the  bridges  of  the  Romans  still 
extant  and  of  those  of  ancient  and  mediaeval  times  of  which  there  are  remains 
or  records,  that  the  foundations  were  carefully  considered. 

The  most  ancient  form  was  likely  begun  by  dumping  in  loose  stones  until 
the  surface  of  the  water  was  reached  and  the  masonry  could  then  be  com- 
menced without  the  necessity  for  any  method  of  excluding  the  water.  The 
oldest  civilizations  were  in  tropical  or  semi-tropical  countries  where  the 
streams  are  dry  beds  for  many  months  in  the  year  and  suitable  foundations 
were  easily  made  without  water  to  contend  with.  Where  the  bottom  of  the 
stream  was  rock,  the  engineering  could  be  very  little  improved  upon  to-day, 
and  even  where  there  was  shallow  water  on  rock  bottom,  the  piers  were  well 
founded  in  the  shallowest  places,  the  bridge  often  winding  across  the  stream 
in  serpentine  form,  similar  to  the  bridge  over  the  river  Karun,  at  Shuster, 
Persia.  Fig.  1. 

The  arch  was  developed  to  such  an  extent  by  the  Romans,  and  the  spans 
were  increased  to  a  length  which  rendered  the  construction  of  piers  in  the 
water  unnecessary  for  short  bridges,  the  abutments  or  skewbacks  being 
without  the  stream  on  either  bank. 

The  difficulty  of  founding  piers  in  midstream  was  doubtless  the  con- 
trolling cause  for  the  larger  spans,  such  as  the  one  built  at  Trezzo,  over  the 
river  Adda,  by  order  of  the  Duke  of  Milan,  sometime  prior  to  the  year  1390. 
The  span  at  low  water  was  251  feet,  the  single  arch  being  of  granite  in  two 


THE   COFFER-DAM   PROCESS   FOR   PIERS.  3 

courses.  The  placing  of  a  middle  support  was  doubtless  found  to  be  imprac- 
ticable and  caused  the  design  of  an  arch  which  has  never  been  equaled  or 
eclipsed.  Fig.  2. 

The  construction  of  roads  has  ever  been  the  harbinger  of  civilization, 
and  with  the  spread  of  civilization  came  a  demand  for  the  improvement  of 
means  of  communication.  The  engineer  was  called  upon  to  construct  better 
and  greater  bridges  in  a  permanent  manner,  which  led  to  the  origin  and 
development  of  the  four  methods  for  founding  in  water  that  were  used  in 


FIG.  2. — BRIDGE  OVER  THE  ADDA,  AT    TREZZO,    MILANESE,    A    PROBABLE    RESTORATION. 
THIi  SHADED  PORTION    OF  ARCH  RINGS  IS  A  I,  I,    THAT  REMAINS. 

olden  times.  These  may  be  classified  as,  first,  the  method  with  open  cais- 
sons; second,  the  use  of  piles  with  a  capping  of  coarse  concrete  about  the 
tops;  third,  the  use  of  piles  after  the  manner  of  the  French  encaissement; 
and  fourth,  the  use  of  coffer-dams.  A  fifth  method  might  be  added,  in 
which  the  bridge  was  built  on  dry  land  adjacent  to  the  stream,  and  the  river 
diverted  to  a  new  channel  afterwards  excavated  under  the  completed  struc- 
ture. This  is,  however,  an  avoidance  rather  than  a  solution,  unless  the  river 
is  to  be  diverted  in  the  course  of  its  improvement. 

The  first  method,  as  described  in  old  treatises  or  accounts,  consisted  of 
little  more  than  baskets  formed  of  branches  of  trees,  weighted  with  stone  to 
sink  them,  and  after  sinking  filled  with  loose  stone  to  near  low  water  level, 


4  THE   COFFER-DAM  PROCESS  FOR   PIERS. 

where  the  masonry  could  be  commenced.  These  baskets  were  similar  in 
construction  to  the  mattresses  used  in  the  bank  revetment  of  the  Mississippi 
or  the  bamboo  casings  used  by  the  Japanese  to  hold  stones  in  place  on  bank 
protection. 

An  improvement  was  effected  by  using  in  place  of  baskets,  boxes  or  small 
open  caissons  which  were  sunk  and  filled  in  the  same  manner,  several  being 
used  for  one  pier.  This  was  the  method  used  at  Black  friars  bridge  and 
also  at  Westminister  bridge,  over  the  Thames,  and  has  been  much  used  in 
recent  times,  the  caisson  being  built  large  and  strong  enough  for  the  entire 
pier,  which  is  built  up  as  the  caisson  sinks. 

The  second  method  consisted  of  driving  piles  over  the  area  of  the  foun- 
dation until  the  heads  were  below  low  water  level,  and  spaced  at  distances 


FIG.  3. — TEN  DAYS  TO  CONSTRUCT;  LENGTH  ABOUT  A  QUARTER  MII.E;  DEPTH  WATER 

16';  WIDTH,  25';  BEAM,  2X  THICK;  ABOUT  50  PIERS. 

apart  as  required  by  the  nature  of  the  bottom,  similar  to  the  methods  in 
vogue  to-day.  The  heads  of  the  piles  were  not  driven  to  the  same  level, 
however,  and  were  incased  in  a  form  of  coarse  concrete  such  as  was  used  by 
the  Romans,  but  what  is  now  called  beton.  This  was  leveled  up  and  on  it 
was  laid  the  stone  for  the  footing  course  of  the  pier. 

The  third  method  of  encaissement  was  probably  an  improvement  of  the 
dumping  in  of  loose  stone  on  which  to  place  the  pier,  and  consisted  in  inclos- 
ing the  space  for  the  pier  with  sheet  piling,  after  which  the  loose  material 
was  removed  from  the  bottom  as  much  as  possible  and  the  stone  dumped 
inside  until  nearly  up  to  low  water,  at  which  time  the  pier  could  be  begun. 


THE   COFFER-DAM  PROCESS  FOR   PIERS.  5 

These  last  two  methods  doubtless  met  with  much  favor  owing  to  the 
familiarity  with  pile  driving,  in  which  the  Romans  especially  were  proficient. 
Caesar's  bridge  over  the  Rhine  was  built  entirely  on  piles,  and  in  a  view  of  it 
after  the  old  print  in  the  Museum  de  St.  Germaine,  is  pictured  a  pile  driver 
on  a  float  in  position  for  driving.  Fig.  3. 

This  third  method  was  the  early  type  of  the  crib  which  has  been  such  a 
factor  in  the  building  of  the  earlier  foundations  over  our  American  rivers. 
Crossed  timbers  laid  up  crib  fashion  with  rectangular  openings  or  cells 
between  the  timbers  were  sunk  and  filled  with  broken  stone  on  which  to 
build  the  pier. 

These  methods  were  all  deficient  in  affording  no  means  of  seeing  or  mak- 
ing a  careful  examination  of  the  bottom  on  which  the  foundation  was  to  be 
placed,  and  with  the  advent  of  more  permanent  structures  of  greater  magni- 
tude the  coffer-dam  came  into  use.  This  allowed  the  bottom  to  be  freed 
from  water  and  after  a  careful  examination  and  preparation  of  the  founda- 
tion, the  work  could  proceed  in  the  dry  until  above  water  level. 

The  pneumatic  caisson  is  now  in  general  use  for  all  foundations  that 
must  go  to  any  considerable  depth  below  the  water  and  has  even  been  used 
in  some  instances  where  the  depth  was  slight,  but  where  for  various  reasons 
it  was  deemed  expedient  louse  compressed  air  caissons.  Recent  expressions 
from  some  engineers  of  high  standing  would  indicate  that  they  do  not  con- 
sider it  good  practice  to  use  coffer-dams  in  any  case,  one  making  the  state- 
ment that  he  had  not  used  a  coffer-dam  for  thirty  years,  while  another 
seemed  to  think  it  a  matter  to  be  left  to  the  pleasure  of  the  contractor.  That 
the  use  of  this  method  has  gotten  into  disfavor  seems  to  be  beyond  question 
and  it  will  be  the  purpose  of  the  succeeding  pages  to  learn  to  some  extent 
why  this  is  so,  but  mainly  to  show  from  successful  examples  how  to  pro- 
ceed, that  success  instead  of  failure  may  result.  Any  attempt  to  account  for 
the  origin  of  the  coffer- dam  process  would  be  futile,  inasmuch  as  the  savage, 
wishing  to  free  a  space  from  water,  doubtless  banked  up  earth  about  the 
area  and.  scooping  out  the  water  with  his  hands,  laid  the  ground  bare  for 
inspection.  From  so  simple  a  beginning,  the  first  method  likely  to  occur  to 
a  mind  capable  of  reasoning,  can  readily  be  imagined  the  course  of  develop- 
ment of  coffer-dams. 

The  most  simple  form  in  use  at  the  present  time,  where  the  water  is 
quiet,  is  shown  in  the  Fig.  4,  and  consists  principally  of  a  bank  of  earth 
which  is  made  thick  enough  to  be  nearly  or  quite  impervious  to  water,  the 
earth  being  prevented  from  caving  into  the  excavation  by  piles  supporting 
a  timber  casing.  Some  of  the  recorded  examples  of  the  early  use  of  this 
process  are  of  interest  in  illustrating  the  care  which  was  bestowed  upon 
their  construction  in  important  works  and  will  call  attention  to  that  incess- 
ant care  which  is  necessary  to  success  in  any  work  of  this  character. 


6  THE   COFFER-DAM  PROCESS  FOR   PIERS. 

Robert  Stevenson,  the  great  English  engineer,  thought  it  not  beneath 
his  dignity  to  give  full  instructions  as  to  the  construction  of  the  coffer-dams 
for  the  Hutcheson  bridge  over  the  Clyde  at  Glasgow.  The  bridge  consisted 
of  five  arch  spans,  the  total  length  between  the  abutments  being  404  feet 
and  the  width  38  feet.  The  four  piers  were  from  11  to  12  feet  in  thickness, 
being  designed  to  take  up  the  arch  thrust,  and  48  feet  in  length  at  the  foot- 


FIG.  4. — A  PRIMITIVE  SOLUTION. 

ing.  The  specifications  written  at  Edinburgh  in  April,  1828,  are  so  explicit 
that  they  will  be  quoted  in  full  on  this  point:  "It  having  been  ascertained 
by  boring  and  mining  that  the  subsoils  of  the  bed  of  the  river  consist  of 
gravel,  sand  and  mud  to  the  depth  of  27  feet  and  upwards,  it  becomes 
necessary  to  prepare  foundations  of  pile  work  for  the  bridge;  and,  therefore, 


THE   COFFER-DAM   PROCESS  FOR    PIERS.  7 

to  insure  the  proper  and  safe  execution  of  the  works,  coffer-dams  are  to  be 
constructed  around  each  of  the  foundation  pits  of  the  two  abutments  and 
four  piers  of  such  dimensions  as  to  afford  ample  space  for  driving  piles,  fix- 
ing wale  pieces,  laying  platforms,  pumping  water,  and  setting  the  masonry; 
and  likewise  for  the  construction  of  an  inner  or  double  coffer-dam  should 
this  ultimately  be  found  necessary.  The  framework  of  the  coffer-dams  is  to 
consist  of  not  less  than  two  rows  of  standard  or  gauge  and  sheeting  piles, 
kept  at  not  less  than  three  feet  apart  for  the  thickness  of  a  puddle  wall  or 
dyke,  which  space  is  to  be  dredged  to  a  depth  of  not  less  than  nine  feet  under 
the  level  of  the  summer  watermark  above  described,  before  the  sheeting 
piles  are  driven.  The  gauge  or  standard  piles  are  to  measure  not  less  than 
24  feet  in  length  and  10  inches  square.  They  are  to  be  placed  three  yards 
apart  and  driven  perpendicularly  into  the  bed  of  the  river  to  the  depth  of 
sixteen  feet  under  the  level  of  the  summer  watermark,  thereby  leaving 
eight  feet  of  their  length  above  that  mark.  Runners  or  walepieces  of  tim- 
ber nine  inches  square  are  then  to  be  fitted  on  both  sides  of  each  row  of 
gauge  piles,  to  which  they  are  to  be  fixed  with  two  screw  bolts  of  not  less 
than  one  inch  in  diameter,  passing  through  each  of  the  gauge  piles.  One 
set  of  these  inside  and  outside  walepieces  is  to  be  placed  at  or  below  the  level 
of  summer  watermark,  and  the  other  set  within  one  foot  of  the  top  of  each 
row  of  said  piles,  the  whole  to  be  fixed  with  screw  bolts  in  the  manner  above 
described.  The  walepieces  are  to  be  four  and  one-half  inches  apart  in  order 
to  receive  and  guide  the  sheeting  piles.  This  is  to  be  effected  by  notching 
the  walepieces  into  the  gauge  piles.  The  sheeting  piles  are  to  be  21  feet  in 
length,  4^  inches  in  thickness,  and  not  exceeding  9  inches  in  breadth. 
They  are  to  be  closely  driven,  edge  to  edge,  along  the  space  left  between 
the  walings,  and  each  compartment  of  the  sheeting  between  the  gauge  piles 
is  to  be  tightened  with  a  key  pile.  The  coffer-dam  frames  are  to  be  properly 
connected  with  stretchers  and 'braces  before  commencing  the  interior  exca- 
vation. Each  coffer-dam  is  to  be  provided  with  a  draw-sluice,  fourteen 
inches  square  in  the  void,  with  a  corresponding  conduit  passing  through  the 
puddle  dyke  at  the  level  of  summer  watermark.  To  render  the  coffer-dams 
water  tight  the  whole  excavated  space  between  the  two  rows  of  piling  is  to 
be  carefully  cleared  of  gravel,  sand  or  other  matters,  to  the  specified  depth, 
and  clay  well  punned  or  puddled  is  then  to  be  filled  in  and  carried  up  to  the 
level  of  the  top  of  the  sheeting  piles.  But  if  it  shall,  notwithstanding,  be 
found  that  the  single  tiers  of  coffer-dam  do  not  keep  the  foundation  pits  suf- 
ficiently free  of  water  for  building  operations,  the  water  must  either  be 
pumped  out  and  kept  perfectly  under  by  steam  or  other  power,  or  else 
excluded  by  the  construction  of  a  second  tier  of  coffer-dam  similar  in  con- 
struction to  the  first.  For  the  foundation  pits  of  the  two  abutment  piers  on 
either  side  of  the  river  it  is  not  expected  that  more  will  be  required  on  the 


8 


THE   COFFER-DAM  PROCESS   FOR   PIERS. 


landward  side  for  keeping  up  the  stuff  than  a  single  row  of  gauge  and  sheet- 
ing piles;  but  if  the  engineer  shall  find  other  works  necessary  upon  opening 
the  ground  they  must  be  executed  by  the  contractor  and  shall  be  paid  for 
agreeably  to  the  contract  schedule  of  prices  for  the  regulation  of  extra  and 
short  works.  The  stuff  within  the  coffer-dams  is  to  be  excavated  to  the 
depth  of  ten  feet  under  the  level  of  summer  watermark  for  each  of  the  piers 
and  eight  feet  for  each  of  the  abutments." 

The  present  practice  of  leaving  all  this  to  a  contractor,  whose  idea  is  too 
often  to  sacrifice  everything  to  cheapness,  appears  in  very  unfavorable  con- 
trast to  this  careful  description. 

An  article  on  founding  by  means  of  coffer-dams,  published  in  1843, 
gives  directions  for  placing  a  coffer-dam  in  forty  feet  of  tide  water;  and 


FIG.  5. — COFFER-DAM   IN   TIDEWATER. 

although  the  engineer  of  to-day  would  use  some  other  method  for  such  a 
depth,  an  illustration,  Fig.  5,  and  short  description  of  it  are  given,  as  ideas 
may  be  gained  for  application  to  ordinary  works. 

The  water  was  assumed  at  ten  feet  deep  for  low  tide,  twenty-eight  feet 
at  high  tide,  with  twelve  feet  of  sand  and  gravel  to  be  removed  to  expose  the 
clay  on  which  the  pier  was  to  rest.  Four  rows  of  piles  were  to  be  driven 
around  the  area,  the  outer  row  to  within  one  foot  of  low  water,  the  two  rows 
in  the  middle  to  within  three  feet  of  high  water,  the  inner  row  to  eleven  feet 
above  low  water,  and  all  to  be  down  five  feet  into  the  clay.  The  outer  row 
of  piles  to  be  six  by  twelve  inches,  the  two  rows  in  the  middle  twelve  by 
twelve  inches,  and  the  inner  row  eight  by  twelve  inches;  all  driven  close 
together  and  to  have  walingpieces,  braces  and  brace  rods  as  shown  in  cross 
section.  The  rows  to  be  six  feet  apart  and  to  be  filled  in  between  with  a 
puddle  of  clay  mixed  with  sand  and  gravel. 

The  report  of  W.  Tierney  Clark,  the  engineer  of  the  Buda  Pesth  suspen- 
sion bridge,  gives  an  account  of  what  are  probably  the  largest  bridge  coffer- 


THE    COFFER-DAM   PROCESS   FOR   PIERS.  9 

dams  ever  constructed.  Some  other  method  would  now  be  used  for  such  a 
location,  but  this  fact  will  not  detract  from  the  lessons  that  may  be  drawn 
from  them. 

The  Danube  was  crossed  at  Buda  Pesth  previous  to  the  year  1837  by 
means  of  a  bridge  of  boats  which  had  to  be  taken  up  during  the  winter  and 
the  passage  made  by  ferry  or  on  the  ice,  so  that  for  six  months  of  each  year 
there  was  great  risk  in  crossing  and  frequent  loss  of  life.  The  building  of  a 
permanent  bridge  was  brought  about  through  the  efforts  of  the  Count 
Szechenyi,  who,  as  a  member  of  a  committee,  proceeded  to  England  in  1832 
and  after  a  careful  investigation  of  existing  works  decided  upon  the  con- 
struction of  a  suspension  bridge.  The  greatest  question  for  solution  was 
the  founding  of  the  two  towers  in  a  river  like  the  Danube,  where  the  ice 


Trans\crtt  Sfctic 


J     Ccfler  Dam' 


FIG.  6. — BUDA     PESTH     SUSPENSION     BRIDGE. 

throughout  the  long  winter  wrought  havoc  with  everything  in  reach.  The 
ice  in  the  river  in  February,  1838,  was  from  six  to  ten  feet  thick  near  the 
site  of  the  proposed  piers.  On  March  9  a  movement  occurred  across  the 
whole  river  and  for  a  length  of  350  yards,  the  whole  moving  in  a  solid 
mass.  On  March  13  it  moved  again  400  yards  and  three  hours  later  a  gen- 
eral breaking  began.  The  ice  piled  up  on  the  shoals  causing  a  sudden  rise 
to  twenty-nine  feet  five  inches  above  zero,  and  while  it  was  at  this  height 
for  only  a  few  hours,  it  is  recorded  that  a  great  part  of  Buda  and  two-thirds 
of  Pesth  were  destroyed  and  many  lives  lost. 

The  extraordinary  design  of  the  coffer-dams  can  the  more  readily  be 
understood  after  this  description,  it  being  doubted  by  many  persons  at  that 
time  whether  piers  could  be  placed  in  the  river  by  any  means.  Fig.  6. 


10  THE   COFFER-DAM  PROCESS  FOR   PIERS. 

The  drawings  reproduced  are  of  coffer-dam  No.  3  which  was  about  72 
feet  in  width  and  about  136  feet  in  length  inside  the  puddle  walls,  there 
being  two  puddle  chambers,  each  five  feet  in  width.  From  a  point  about 
thirteen  feet  above  the  clay  on  which  the  tower  was  to  rest,  was  an  inside 
wall  of  sheet  piling,  this  space  being  nearly  filled  after  excavating,  with  a  bed 
of  concrete.  The  piling  of  each  row,  from  forty  to  eighty  feet  in  length, 
was  all  carefully  sized  to  fifteen  inches  square,  shod  with  iron  and  driven 
close  together,  penetrating  twenty  feet  below  the  bed  of  the  stream  or  forty 
feet  below  the  zero  level.  The  framing  of  the  ice  breaker  and  the  bracing 
within  the  dam  was  of  enormous  strength.  The  number  of  piles  driven  in  the 
four  coffer-dams  reached  the  enormous  total  of  5,224,  and  of  the  1,227  driven 
in  darn  No.  3,  16^  Per  cent,  were  drawn  and  redriven.  These  piles  and  the 
timber  were  obtained  from  the  forests  of  Bavaria  and  Upper  Austria.  Fig.  7. 

The  first  pile  on  dam  No.  3  was  set  on  April  8,  1842,  but  owing  to  the 
difficulties  encountered  it  was  not  finished  until  three  years  later — April  4, 
1845.  From  six  to  seven  days  were  occupied  at  the  first  in  driving  a  pile 
to  a  depth  of  five  or  six  feet  into  the  clay,  but  as  the  work  progressed  the 
difficulty  increased,  the  operation  of  driving  one  pile  consuming  from  twelve 
to  fourteen  days,  many  piles  breaking  short 'off  so  they  could  not  be  with- 
drawn, and  the  gravel  was  dredged  out  from  behind  and  a  second  row  driven. 
The  report  further  describes  the  difficulty  of  the  work:  "The  dredging  for 
the  No.  3  dam  was  carried  on  to  the  average  depth  of  forty-four  feet  from 
the  top  of  the  outer  row  of  piles,  leaving  about  ten  feet  of  gravel  to  drive 
through,  and  extra  piles  were  driven  where  the  gravel  found  its  way  between 
the  piles,  as  well  as  where  it  was  known  the  piles  were  not  driven  to  the 
proper  depth,  or  were  broken  or  otherwise  injured.  As  the  gravel  was 
dredged  out  to  the  above  depth,  the  inner  and  middle  row  of  piles  were 
driven,  and  a  great  part  of  them  got  down  as  was  supposed  to  the  requisite 
depth.  The  work  was  carried  on  in  the  above  manner  until  the  7th  of  No- 
vember, when  from  the  appearance  of  several  piles  which  were  pulled  up, 
and  from  other  causes,  it  became  apparent  that  the  outer  row  was  in  a  much 
worse  state  than  had  been  expected  and  was  almost  a  matter  of  certainty, 
that  those  piles  which  had  taken  ten  or  twelve  days  to  get  down  were  not 
driven  to  the  proper  depth  by  at  least  three  or  four  feet,  having  upset  or  lost 
their  points  to  that  extent.  There  was  likewise  every  reason  to  believe  that 
many  of  them  were  broken  or  dangerously  crippled.  Added  to  this  the 
Danube  was  rising,  and  at  the  late  time  of  the  year,  with  winter  rapidly 
approaching,  the  general  appearance  of  the  dam  was  anything  but  satisfac- 
tory. Upon  mature  consideration  the  only  course  appeared  to  be  to  drive  a 
much  greater  number  of  piles  than  was  at  first  calculated  upon,  and  another 
complete  row  of  piles  was  driven  all  round  at  intervals  of  fifteen  inches  apart, 
and  in  some  cases  double  and  triple  piles  were  driven  during  the  progress  of 


12  THE   COFFER- DAM   PROCESS  FOR   PIERS. 

the  dredging.  At  the  commencement  of  the  driving  a  few  were  got  down 
to  the  depth  of  fifty-seven  or  fifty-eight  feet,  being  from  three  to  four  feet  in 
the  clay;  but  as  the  gravel  began  to  get  compressed  many  of  them  would 
not  penetrate  more  than  fifty- four  or  fifty-five  feet,  the  sharp  angular  gravel 
overlying  the  clay  appearing  to  be  compressed  into  a  substance  as  hard  as 
rock." 

The  puddle  used  was  clay  mixed  with  about  one-third  clean  gravel,  it 
having  been  found  to  set  quite  solid,  from  experiments  made  by  sinking 
specimens  in  the  Danube.  When  leaks  occurred  they  were  closed  by  driv- 
ing square  timbers  down  thirty  or  forty  feet  into  the  puddle  to  pack  it  or 
by  driving  new  piles  to  close  the  cracks  and  in  some  cases  by  driving  sheet 
piling. 

Experiences  of  this  nature  led  to  the  disuse  of  coffer-dams  for  founda- 
tions to  such  depths,  but  a  very  small  percentage  of  the  care  exercised  and 
the  persistence  shown  in  this  work  would  lead  to  greater  success  on  ordi- 
nary foundations. 

The  class  of  work  to  which  coffer-dams  may  still  be  applied  will  be  shown 
in  the  succeeding  pages  and  the  examples  from  actual  practice  will  show  in 
some  measure  the  care  that  must  be  exercised  in  the  first  construction  to 
prevent  failure,  and  the  expedients  adopted  to  overcome  unavoidable  acci- 
dents. 

"In  every  man's  mind,  some  images,  words  and  facts  remain,  without 
effort  on  his  part  to  imprint  them,  which  others  forget,  and  afterwards  these 
illustrate  to  him  important  laws." 


ARTICLE    II. 

THE    COFFER-DAM    PROCESS    FOR    PIERS. 


CONSTRUCTION    AND    PRACTICE. 


HE  exact  definition  of  the  term  coffer-dam — "a  water-tight 
inclosure,  from  which  the  water  is  pumped  to  expose  the 
bottom  and  permit  the  laying  of  foundations" — is  the 
class  of  structure  which  is  to  be  considered,  although  in 
the  construction  of  them  cribs  or  caissons  may  be  employed  and  utilized;  the 
essential  purpose  being  to  form  an  inclosure  as  nearly  watertight  as  possible 
in  order  that  the  expenditure  of  power  for  pumping  out  the  water  may  be  of 
small  amount. 

The  attainment  of  this  when  the  water  is  shallow  and  has  little  current 
we  have  seen  to  be  easily  accomplished  by  means  of  a  bank  of  clay  or  clayey 
gravel. 

This  form  may  also  be  employed  in  still  water  up  to  about  four  feet  in 
depth  by  the  addition  of  sheet  piling  or  a  casing  supported  by  ordinary  piles 
to  prevent  the  embankment  from  caving  into  the  excavation.  Where  the 
bottom  is  of  soft  mud  or  porous  material  over  a  solid  clay  or  gravel,  as  much 
as  possible  of  the  porous  material  should  be  removed  before  forming  the 
embankment,  thus  preventing  leakage  underneath.  In  very  shallow  water 
this  can  be  accomplished  by  shoveling  and  with  large  hoes  or  scoops,  but 
with  several  feet  of  water  to  contend  with,  some  form  of  dredge  or  scraper 
must  be  employed.  A  very  convenient  form  of  scraper  used  by  M.  L.  Byers 
on  the  Cinti.  &  Mus.  Valley  Railway  is  described  in  Vol.  31  of  the 
''Transactions  of  the  American  Society  of  Civil  Engineers,"  and  consists  of  old 
boiler  iron,  strengthened  by  three  ribs  of  light  iron  rail  as  shown  in  Fig.  8. 
This  was  operated  by  a  double  drum  20  horse-power  Mundy  hoisting  engine, 
with  the  towing  line  running  directly  from  one  drum  to  the  scraper  and  the 
back  line  from  the  other  drum  over  a  sheave  to  the  front  of  the  scraper.  The 
excavating  averaged  about  forty-five  yards  of  material  each  day  during 
twelve  days'  work.  The  weight  of  the  device  was  about  one  thousand 
pounds. 

Where  the  material  is  very  soft,  a  hand  dredge  called  a  spoon  will  accom- 
plish the  work  at  about  the  same  cost  as  excavating  on  dry  land.  The 
spoon  usually  consists  of  a  long  pole,  having  a  cutting  ring  fastened  at  one 
end,  and  to  this  ring  is  attached  a  canvas  bag  to  contain  the  excavated  ma- 

13 


THE   COFFER-DAM  PROCESS  FOR  PIERS 


terial.  The  ring  is  hung  from  a  derrick  with  a  set  of  falls,  being  guided  with 
the  pole,  as  it  is  dragged  forward  by  the  derrick  through  the  material  to 
be  excavated. 

Excavating  may  be  done  on  all  the  larger  rivers  by  employing  the  sand 
or  gravel  diggers  which  are  most  always  to  be  found,  the  dredging  being 
accomplished  by  means  of  a  series  of  buckets  on  a  belt  or  on  chains  operated 
through  a  well  in  the  bottom  of  a  barge.  Dredging  by  machinery  on  a  large 
scale  will  be  considered  later  on  in  some  detail. 

The  method  of  embankment  is  sometimes  employed  for  greater  depths 
than  four  feet  and  in  some  instances  successfully. 

The  Chanoine  dams  on  the  Great  Kanawah  River  required  substantial 
foundations  beneath  the  water,  and  to  accomplish  this  Addison  M.  Scott,  the 

resident  engineer, 
employed  log  cribs 
about  the  spaces,  with 
earth  banked  up  on 
the  outside.  This 
work  is  described  in 
the  report  of  the  Chief 
of  Engineers  for  1896. 
The  site  of  the 
navigation  pass  of 
dam  No.  11  including 
the  center  pier,  re- 
quired a  coffer-dam  90 
feet  wide  and  330  feet 
long  inside.  (Fig. 9.) 
This  area  including 
the  necessary  room  for 
the  cribs,  was  dredged 
out  to  hardpan  from 
20  to  24  feet  below  low 
water.  The  log  cribs 
which  contained  about 
84,000  lineal  feet  of 

logs,  were  sunk  in  sections  19  feet  wide  and  20  feet  long.  They  were 
sheathed  up  to  about  three  feet  above  low  water,  with  sheet  piling  in 
three  layers,  on  the  Wakefield  system.  The  driving  was  accomplished  by 
attaching  an  eighty-pound  weight  to  an  Ingersoll-Sergeant  drill  run  by  steam 
and  utilizing  the  reciprocating  motion  by  attaching  the  drill  with  clamps 
to  the  tops  of  the  sheathing,  following  it  down  as  it  was  driven,  after  the 
manner  of  the  Nasmyth  steam  pile  hammer.  This  device,  which  is  one  of 


FIG.  8.— SCRAPER    DREDGE. 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  15 

the  most  ingenious  ever  devised  for  the  purpose,  was  arranged  by  the  con- 
tractor's engineer,  S.  H.  Reynolds,  and  was  a  complete  success. 

The  tops  ol  the  cribs  were  ten  feet  above  low  water,  and  the  bottoms 
rested  on  the  hardpan,  making  a  total  height  of  from  thirty  to  thirty-four 
feet. 

The  cribs  were  tilled  with  sand  and  gravel  that  had  been  dredged  out, 


FIG.  9, — COFFER-DAM    AT   DAM    NO.   1 


GREAT    KANAVVAH    RIVER. 


but  the  outside  was  banked  up  with  selected  clay  and  dredged  material, 
which  was  protected  by  a  layer  of  riprap  up  to  about  low  water. 

When  the  coffer  dam  was  first  pumped  out  several  leaks  were  developed, 
but  after  one  week  in  perfecting  the  details  the  pumps  were  started  regu- 
larly and  no  serious  trouble  was  had  afterward.  This  is  only  one  of  a  ser- 
ies of  coffer-dams  which  have  been  constructed  on  the  several  dams  in  this 
river,  and  owing  to  the  care  exercised  good  results  were  obtained  uniformly. 

The  construction  of  a  similar  piece  of  work  on  the  Ohio  river  was  begun 
by  Major  R.  L.  Hoxie,  corps  of  engineers,  and  is  described  in  the  report  of 
1895:  "It  was  originally  planned  to  enclose  the  site  of  the  dam  and  lock 
within  a  coffer-dam,  and  work  was  commenced  upon  that  basis.  But  on 


10 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


attempting  to  pump  out  the  inclosure,  it  was  found  that  water  came  in  in 
large  quantities,  not  only  under  the  dam  but  from  springs  in  the  bottom, 
and  all  attempts  to  close  these  by  dumping  clay  and  gravel  was  a  failure. 
The  area  inclosed  by  the  dam  was  about  600  by  200  feet  or  about  three  acres 
of  river  bottom.  The  deposit  of  sand  and  gravel  overlying  the  rock  was 
about  thirty-five  feet  thick,  the  rock  being  forty-five  feet  below  the  water 
level,  while  the  plans  required  an  excavation  twenty  feet  deep  below  this 
water  surface.  The  bottom  deposit  had  been  worked  over  for  years  by  sand- 
diggers  who  threw  back  the  large  stones  and  coarse  gravel  after  removing 


FIG.  10. — CRIB  COFFER-DAM;   CHICAGO,  BURLINGTON  AND  QUINCY  RAILROAD. 

the  fine  sand,  this  work  resulting  in  a  very  permeable  bottom,  with  possible 
channels  of  comparatively  large  dimensions  extending  to  unknown  distances 
beyond  the  limits  of  the  coffer-dam." 

This  is  perhaps  the  most  frequent  source  of  failure  of  a  well  constructed 
coffer-dam  and  should  always  be  guarded  against  by  removing  as  much  of 
the  porous  material  as  possible,  by  dredging  before  the  construction  of  the 
coffer-dam  is  begun. 

Cribs  are  very  easy  to  construct,  usually  very  substantial,  and  easy  to 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  1 7 

make  use  of  by  floating  to  position  and  then  sinking  in  place.  A  very  sim- 
ple form  that  has  been  used  on  the  Chicago,  Burlington  &  Quincy  railroad 
is  described  by  E.  J.  Blake,  chief  engineer.  Where  the  water  is  shallow 
they  have  been  built  in  the  form  shown  (Fig.  10)  of  fence  boards  spiked 
one  piece  on  another;  with  deeper  water  they  are  made  of  heavier  timber 
2"x8"  or  2"xlO".  They  are  built  on  the  water  and  are  tied  across  at  inter- 
vals by  pieces  spiked  through  the  wall,  wThich  pieces  should  be  carefully 
fitted  to  prevent  leakage.  In  some  cases  where  the  bottom  is  soft,  instead 
Of  dredging,  a  bottom  is  added  to  the  crib  to  prevent  the  filling  from  squeez- 
ing its  way  out  from  under  the  edge. 

When  the  crib  has  reached  bottom,  being  sunk  by  weighting  it  down  if 

n 


FIG.  11. — ST.  LAWRENCE    RIVER    BRIDGE    CRIB    AND    COFFER-DAM,    CANADIAN 

PACIFIC    RAILWAY. 

necessary,  the  chambers  are  filled  with  clay  puddle  and  clay  is  banked  up 
around  the  outside  to  prevent  water  running  under.  The  crib"  is  made  large 
enough  so  that  the  excavation  will  leave  an  easy  slope  to  the  inner  edge  of 
the  timber  work.  This  form  can  be  made  to  conform  readily  to  the  contour 
of  the  bottom  by  starting  the  layers  of  timber  at  different  elevations.  No 
leakage  has  been  experienced  except  what,  can  readily  be  kept  under  control 
with  ordinary  sized  centrifugal  pumps.  The  cost  of  construction  is  gener- 
ally a  minimum,  as  there  are  usually  plenty  of  old  timbers  available  for  use 
from  the  railroad  yards. 


iS 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


Cribs  constructed  in  a  similar  manner  but  with  only  one  wall  of  timber 
have  been  used  successfully  on  the  Canadian  Pacific  Railway  by  P.  Alex. 
Peterson,  chief  engineer. 

The  bracing  is  very  efficiently  attached  by  dovetailing  it  into  the  sides, 
while  the  form  of  the  crib  enables  it  to  withstand  the  force  of  the  current 
and  the  ice.  The  projections  on  the  inside  are  to  prevent  the  water  from 
forcing  its  way  up  between  the  sides  and  the  concrete  filling  when  the  dam 
is  pumped  out.  These  projections  answered  their  purpose  very  effectually , 
and  when  the  dam  was  pumped  out  it  remained  dry  enough  to  lay  the 
masonry  without  any  additional  pumping. 

Illustrations  are  given  of  a  crib  of  this  character  which  was  used  on  the 
St.  Lawrence  river  (Fig.  11)  similar  ones  being  used  for  the  other  piers  of  the 
same  bridge,  and  of  the  crib  used  for  the  Arnprior  bridge.  (Fig.  12.)  This 
shows  the  concrete  which  was  deposited  on  which  to  found  the  masonry,  and 


3 


I 


E 


FIG.    12. — ARNPRIOR     BRIDGE     CRIB   AND    COFFER-DAM,    CANADIAN    PACIFIC*  RAILWAY. 

which  formed  a  watertight  bottom  so  that  the  crib  could  be  pumped  out  for 
the  laying  of  the  stone. 

The  practice  on  the  Atchison,  Topeka  &  Santa  Fe  railroad  has  been 
in  some  respects  similar  to  what  has  been  given.  C.  D.  Purdon,  assist- 
ant chief  engineer,  states  that  cribs  built  of  old  timbers  are  used  when 
such  material  as  stringers  7"xl6"  is  plentiful,  each  course  being  stepped  in 
about  one-half  an  inch  to  give  a  batter.  For  use  in  sand  when  rocks  and 
drift  are  likely  to  be  encountered  a  crib  is  made  by  constructing  a  frame  of  old 
bridge  timbers  and  sheathing  it  with  plank.  (Fig.  13.)  This  is  sunk  by  digging 
out  the  sand,  which  is  shoveled  first  into  box  A,  then  to  boxes  B,  then  to 
C,  and  then  outside.  The  suction  pipe  is  shown  in  dotted  lines,  the  pumping 
being  accomplished  with  a  centrifugal  pump.  This  plan  works  very  sue- 


20  THE   COFFER-DAM  PROCESS  FOR  PIERS. 

cessfully  on  the  streams  in  Colorado  and  New  Mexico  where  the  water  is 
mostly  in  the  sand  and  but  little  shows  as  surface  water. 

The  Arkansas  river  bridge  of  the  St.  Louis  &  San  Francisco  railroad  at 
Tulsa  was  built  over  a  bottom  of  gravel  and  riprap  above  rock,  which  was 
quite  level  and  about  seven  feet  below  low  water.  Cribs  were  constructed 
for  coffer-dams  similar  to  the  one  just  described  and  set  on  the  bed  of  the 
stream.  Clay  from  the  bank  was  dumped  outside  and  as  the  crib  was  dug 
out  and  sunk,  the  clay  followed  down  and  kept  out  the  water. 

When  the  bottom  is  of  clay  or  of  sand  without  obstructions,  sheet  piles, 
either  tongue  and  groove  or  the  Wakefield,  are  driven  around  a  crib. 

Geo.  H.  Pegram,  chief  engineer  of  the  Union  Pacific  system,  has  made  the 
construction  of  coffer-dams  conform  to  available  material  and  local  condi- 
tions. At  the  crossing  of  the  Republican  river  in  Kansas,  where  the  bottom  was 
sandy,  a  single  thickness  of  four-inch  V-shaped  tongue  and  groove  sheet- 
piling,  with  the  usual  guide  piles  and  wales,  served  to  form  a  watertight 
structure. 

Where  a  gravel  bottom  overlaid  a  hard  soapstone,  as  on  some  work  in 
Idaho,  with  seven  feet  of  water  to  contend  with,  the  coffer-dam  was  made  of 
Wakefield  piling,  formed  of  1^-inch  sized  plank.  The  joints  were  tightened 
with  cement;  and  sand,  gravel  and  straw  placed  outside  to  prevent  leaking. 
Wakefield  piling  has  also  been  used  for  clean  rock  bottom,  placed  in  two 
rows  about  the  depth  of  the  water  apart.  Intermediate  cribs  filled  with  rock 
were  used  to  sink  them.  The  ends  of  the  piling  were  sharpened  and  driven 
on  the  rock  until  broomed  up  and  rendered  nearly  watertight,  when  gravel 
mixed  with  straw  was  placed  around  outside  to  close  any  remaining  leaks. 

In  cases  where  ordinary  piling  has  been  driven  and  a  grillage  laid  upon 
them  to  receive  the  masonry,  a  coffer-dam  is  constructed  as  shown  (Fig.  14) 
in  which  to  lay  the  masonry.  The  construction  of  this  is  fully  shown  in  the 
different  views  given. 

Another  form  of  coffer-dam  for  the  same  purpose  was  constructed  by 
Octave  "Chanute  in  laying  the  masonry  of  the  pivot  pier  for  the  Fort  Madison 
bridge  over  the  Mississippi  river,  on  the  line  of  the  Atchison,  Topeka  &  Santa 
Fe  railroad.  (Fig.  15).  This  is  described  in  the  Engineering  News  of  June  2, 
1888,  by  W.  W.  Curtis,  resident  engineer  :  "The  grillage  (for  the  pivot  pier) 
is  four  feet,  three  inches  thick,  the  upper  fifteen  inches  being  dressed  to  an 
accurate  circle  of  the  desired  diameter.  The  coffer-dam  was  footed  against 
these  two  courses  and  was  formed  of  3"x8"pine  plank  staves,  dressed  on  the 
sides  to  a  slight  bevel  around  which  were  placed  seven  wrought  iron  hoops 
4"xTy,  5"x  ",  and  6"xyV'>  similar  to  those  used  for  water  tanks,  and 
screwed  up  tight.  Inside  of  these,  circular  braces  of  plank  were  fitted.  As 
a  water  pressure  of  nineteen  feet  was  to  be  resisted,  additional  security  against 
leakage  was  obtained  by  placing  a  string  of  candle  wicking  vertically  between 


r 


TTTT 


1 


Half   Plan. 


FIG.    14. — COFFERDAM    ON    GKILLAGK  ;    PAYETTE    AND    WEISER    RIVER    BRIDGES. 
UNION    PACIFIC    SYSTEM. 


6'  O" 


6'0' 


>4"x6"*7' 


3"xl2"xiz' 


3  *  12"  x  12' 


View. 


FIG.    14  — COFFER-DAM    ON    GRILLAGE,     PAYETTK   AM)    WEISER    RIVER 
BRIDGES.       UNION    PACIFIC    SYSTEM. 


24  THE   COFFER-DAM  PROCESS  FOR  PIERS. 

each  stave.  When  the  caisson  was  submerged  to  about  full  depth  it  became 
necessary  for  the  steamboat  to  assist  it  into  final  position.  A  12"xl2"  post 
was  bedded  in  the  concrete  in  the  center  of  the  pier,  with  four  braces  run- 
ning to  the  circular  bracing  of  the  sides.  This  makes  a  very  cheap  coffer- 
dam and  was  found  to  work  very  well." 

An  attempt  to  use  a  form  similar  to  this  was  made  in  constructing  the 
Walnut  Street  bridge  at  Philadelphia.  This  is  described  by  Geo.  S.  Web- 
ster, chief  engineer  Bureau  of  Surveys,  in  the  Engineering  News  of  March 
15,  1894:  "In  founding  the  river  piers,  the  Robinson  coffer-dam  was  first 
tried,  but  was  abandoned  after  three  of  them  had  failed  by  collapsing.  This 


Section  o-f  Pier 

FIG.   15. — COFFER-DAM    ON   GRII,I,AGB,   FORT  MADISON    BRIDGE,  ATCHISON,    TOPEKA 

AND   SANTA  FF,  RAILWAY. 

dam  may  be  briefly  described  as  follows  :  A  circular  platform  about  eighty 
feet  in  diameter  supported  upon  piles  at  an  elevation  of  about  four  feet  above 
high  water  was  first  constructed.  Square  piles  of  12"xl2"  yellow  pine  were 
then  prepared  by  spiking  a  3"x4"  timber  flat,  along  the  middle  of  one  side, 
and  two  others  along  the  edges  of  the  opposite  side,  forming  a  tongue  and 
groove  on  each  pile.  The  tops  were  squared  off  and  the  bottom  ends 
pointed  to  a  wedge  shape.  These  piles  were  then  driven  close  together 
against  the  edge  of  the  circular  platform  and  down  to  rock.  Mr.  Robinson's 
idea  was  that  the  mud  overlying  the  rock  would  hold  the  piles  in  position  at 
the  bottom,  and  if  the  top  ends  were  held  by  an  outside  hoop,  the  dam  would 
be  secure  without  internal  bracing  to  resist  collapsing  pressure.  In  the  first 
trial  the  hoop  was  made  of  boiler  iron  some  four  feet  or  more  in  width.  In 
the  second  dam  it  was  formed  of  a  heavy  steel  railway  rail,  and  in  the  third 


THE   COFFER-DAM  PROCESS  FOR  PIERS,  25 

dam  the  hoop  was  the  same  as  in  the  second,  but  it  also  had  a  number  of 
radial  rods  in  addition.  The  first  dam  was  pumped  out  and  held  for  nearly 
an  hour  before  collapsing,  but  the  others  collapsed  before  being  entirely 
pumped  out.  After  the  third  failure  this  form  of  dam  was  abandoned." 

It  would  seem  likely  from  a  comparison  of  the  two  cases,  one  being  en- 
tirely successful  and  the  other  a  failure,  that  had  the  Walnut  street  dam 
been  supplied  with  additional  bands  lower  down  and  provided  with  some 
means  of  tightening,  with  several  internal  bracing  ribs  of  timber,  it  would 
have  proven  a  success.  These  bands  and  ribs  could  likely  have  been  placed 
by  a  diver. 

The  uncertainty  which  always  exists  regarding  any  construction  under 


FIG.    16. — A   CRIB    COFFER-DAM    AFTER    A    FIvOOD. 

water  makes  it  imperative  that  every  precaution  should  be  taken  to  guard 
against  troubles  that  might  arise,  by  making  the  construction  of  no  doubtful 
form  and  in  no  doubtful  manner  from  its  first  inception. 

The  nature  of  the  bottom  will  always  indicate  the  method  of  construc- 
tion which  should  be  adopted  in  a  given  case,  but  it  would  be  rarely  that  the 
preliminary  dredging  could  be  dispensed  with.  It  is  true  that  there  are 
cases  where  there  is  a  deposit  overlying  a  seamy  rock,  and  the  water  will 
find  its  way  along  the  seams,  bubbling  up  in  springs  inside.  Resource  must 
be  had  to  cutting  off  the  flow,  by  puddling  on  the  outside,  sometimes  ex- 
tending the  operations  a  distance  of  a  hundred  feet  or  more  away,  until 
enough  of  the  flow  has  been  stopped  so  that  the  water  can  be  kept  down  b}' 
a  reasonable  amount  of  pumping. 


26  THE  COFFER-DAM  PROCESS  FOR  PIERS. 

The  next  precaution  after  dredging,  is  the  building  of  some  form  of  coffer- 
dam which  shall  effectually  exclude  any  flow  through  the  sides  of  the  dam. 
TJiis  we  have  seen  to  be  accomplished  in  many  cases  by  means  of  a  bank  of 
clay,  or  a  row  of  sheet-piling,  and  in  some  cases  by  a  single  walled  crib.  But 
in  the  last  two  methods  a  supplementary  bank  of  clay  or  clayey  gravel  on 
the  outside  is  necessary  to  prevent  leakage. 

This  bank  may  be  protected  from  wash  by  covering  it  with  clay,  sand  or 
gravel  in  gunny  sacks,  or  by  ripraping  up  to  about  low  water,  as  was  done 
on  the  Kanawah  dams. 

Double  walled  cribs  and  coffer-dams  constructed  with  two  rows  of  water- 
tight sheet  piling,  require  to  be  puddled  with  a  carefully  selected  material. 
While  clay  can  be  used  with  a  good  degree  of  success,  it  will  be  found  better 
to  use  a  clayey  gravel  or  to  mix  the  clay  and  gravel,  as  was  done  at  the 
Buda-Pesth  bridge.  When  a  small  leak  starts  through  a  pure  clay  puddle, 
it  washes  out  the  clay  in  considerable  quantities  and  a  dangerous  leak  is 
soon  developed.  With  the  admixture  of  gravel,  however,  a  leak  is  stopped 
almost  as  quick  as  started  by  the  heavier  gravel  falling  into  and  closing  the 
void. 

It  will  generally  be  found  advantageous  to  use  a  bank  of  clay  outside  of 
a  double  walled  dam,  unless  it  might  be  a  case  where  sheet  piling  has  been 
driven  to  rock,  and  even  then  a  certain  amount  of  material  in  sacks  should 
be  used  to  prevent  wash  or  the  cutting  out  of  the  earth  around  the  sheeting. 

Whatever  excavation  is  taken  out  of  the  interior  of  the  coffer-dam  after  it 
has  been  pumped,  should  be  dumped  at  the  upstream  end  and  corners,  or  to 
fill  any  holes  or  pockets  there  may  be  around  the  sides  or  ends. 

Cutwaters  should  be  added  to  all  coffer-dams  which  are  built  in  rivers 
having  a  swift  current  or  a  heavy  flow  of  ice,  as  was  the  case  at  Buda-Pesth 
and  on  the  Canadian  Pacific  examples.  They  must  also  be  used  in  rivers 
where  the  run  of  drift  with  each  rise  is  of  large  amount.  For  the  purpose  of 
preventing  wash  around  a  dam,  a  cutwater  of  plank  supported  by  a  frame  of 
timber  may  be  constructed  separate  from  the  main  structure,  or  a  V-shaped 
row  of  sheet  piling  driven  up  stream.  On  rock,  a  timber  crib  of  triangular 
shape,  built  of  round  logs,  may  be  sunk  up  stream  and  filled  with  broken 
stone.  Such  a  crib  can  be  utilized  in  anchoring  the  main  crib  of  a  coffer- 
dam, as  was  done  at  St.  Louis,  and  which  will  be  described  in  future  pages. 

More  fitting  language  cannot  be  found  for  closing  words  than  those  used 
in  Wellington's  monumental  work  on  railway  location:  ''The  uncertainty 
as  to  the  exact  requirements  to  be  fulfilled  by  the  works  when  completed  is 
a  disadvantage,  indeed,  which  cannot  be  escaped;  but  the  more  difficult  it  is 
to  reach  absolute  correctness,  the  greater  need  we  have  of  some  guide  which 
shall  reduce  the  unavoidable  guess-work  to  its  lowest  terms,  and  so  save  us 
from  the  manifold  hazards  which  result  from  not  only  guessing  at  facts, but 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  2/ 

at  the  effect  of  those  facts.  Whatever  care  we  use  we  can  never  attempt 
with  success  to  fix  the  exact  point  where  economy  ends  and  extravagance 
begins  ;  but  what  we  can  do  is  to  establish  certain  narrow  limits  in  either 
direction,  somewhere  within  which  lies  the  truth,  and  anywhere  outside  of 
which  lies  a  certainty  of  error." 


ARTICLE   III. 

THE    COFFER-DAM    PROCESS    FOR    PIERS. 

CONSTRUCTION    AND    TRACT  ICE. 

I/SHEN  for  some  reason  the  necessary  care  has  not  been  exercised 
in  the  construction  of  a  coffer-dam  and  in  puddling  it,  or  where 
there  were  discovered  conditions  not  known  before  the  con- 
struction began,  which  rendered  the  work  unsatisfactory  or 
leaky,  it  will  usually  be  found  that  the  mode  of  repair  which 
seems  most  expensive  will  in  the  end  prove  the  cheapest  and 
most  expeditious.  If  the  puddle  proves  leaky,  and  it  be  decided  that  the 
material  was  of  too  porous  a  nature,  the  best  remedy  is  to  dig  out  and  replace 
it  with  better.  Should  it  be  found  that  the  porous  bottom  had  not  been 
removed  to  a  sufficient  depth,  it  may  be  found  necessary  to  dig  out  the  pud- 
dle chambers  and  puddle  deeper,  or  the  leaks  might  be  stopped  by  banking 
up  outside  of  the  dam  with  clay  or  clayey  gravel,  or  perhaps  sand  in  sacks 
would  do  some  good. 

Gravel  will  allow  the  percolation  of  water  even  where  the  head  is  small, 
and  when  a  pressure  of  from  four  feet  upwards  is  brought  upon  it,  the  leak- 
age becomes  considerable  and  difficult  to  control,  so  that  pure  gravel  is  of 
little  service  in  stopping  leaks. 

Hay,  straw,  oats,  crushed  cane  stalks,  rotten  stable  manure,  and  similar 
materials,  mixed  with  the  banking  material,  are  very  efficacious  in  pro- 
ducing tightness,  and  when  applied  to  local  leaks  will  assist  in  closing  them. 
Where  sheet  piling  have  been  used  to  exclude  the  water  and  leaks  still 
occur,  they  can  often  be  closed  by  driving  more  sheeting  to  lap  the  cracks, 
which  may  have  been  widened  out  lower  down  as  the  sheet  piles  were  first 
driven.  This,  we  have  seen,  produced  satisfactory  results  at  Buda-Pesth, 
where  leaks  were  also  closed  by  driving  square  timbers  into  the  puddle  to 
compact  it. 

Clay  can  also  be  forced  down  through  pipes  directly  to  where  the  leakage 
occurs.  The  use  of  this  at  the  Government  Lock  at  Sault  Ste.  Marie  is  de- 
scribed in  the  Engineering  News  of  September  26,  1896:  "The  only  diffi- 
culty encountered  in  the  work  of  excavation  was  due  to  a  leak  in  the  coffer- 
dam, which  flooded  the  lock  pit  and  delayed  the  work  considerably.  The 
cause  of  this  leak  was  found  to  be  a  crevice  in  the  rock  passing  underneath 
the  coffer-dam,  and  despite  all  efforts  to  close  it,  the  flow  of  water  rapidly 
enlarged  the  break  until  about  fifty  feet  of  the  clay  in  the  coffer-dam  had 

28 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


29 


been  washed  away.  The  large  break  was  closed  by  driving  additional  sheet 
piling  and  filling  in  with  brush,  hay,  and  clay  in  sacks.  This,  however, 
failed  to  entirely  stop  the  leak  through  the  crevice,  and  it  was  determined 
to  fill  the  cavity  with  clay.  For  this  purpose  a  3-inch  pipe  was  driven  down 
through  the  coffer-dam  until  its  lower  end  penetrated  the  crevice.  In  this 


A. Cutting  theClay Cylinders  III  Is 

B.  Inserting  the  Cylinders  |  !  !; 

intoTheTutae. 

C.  ForcincjtheOay  down 


' 


V'sSBfikfe^. .'.:.  .-rL      ~-  •  - 


G.1y_  APPARATUS  USED  TO  FORCE  CLAY   INTO  CREVICE  OF   FOUNDATION    ROCK  AND 
CLOSE  LEAK  IN  COFFERDAM. 

pipe  small  cylinders  of  clay  about  one  foot  long  were  placed  and  forced  down 
into  the  cavity  by  means  of  a  plunger  working  in  the  pipe.  The  apparatus 
is  shown  in  the  illustration  (Fig.  17).  As  will  be  seen,  the  plunger,  or  ram- 
mer, is  an  iron  rod  to  the  top  of  which  is  fastened  a  block  of  wood  sliding 
between  the  guides  of  an  ordinary  pile  driver.  The  hammer  of  the  pile 
driver  is  the  weight  which  pushes  down  the  rammer.  This  apparatus  was 


30  THE   COFFER-DAM  PROCESS  FOR  PIERS. 

designed  by  E.  S.  Wheeler,  engineer  in  charge  of  the  work,  and  was  used 
not  only  to  fill  the  crevice,  but  all  along  the  coffer-dam  for  the  purpose  of 
compacting  the  clay  filling.  The  apparatus  proved  most  successful  for  the 
purpose  for  which  it  was  intended." 

The  use  of  rods  for  bracing  in  double  walled  coffer-dams  is  very  often  the 
cause  of  considerable  leakage,  the  wrater  following  along  them  through  the 
puddle.  This  may  be  stopped  by  wrapping  a  band  of  hay  or  straw  around 
the  rod  next  to  the  timbers,  or  by  a  wrapping  of  coarse  cloth,  or  by  a  wood 
washer  having  a  hole  slightly  smaller  than  the  rod,  which  is  forced  through. 

The  walls  of  the  dam  must  always  be  made  tight,  and  this  we  have  seen 
to  be  effected  by  careful  framing  of  sides  and  bracing,  and  it  will  be  seen  in 
a  later  example  how  round  struts  between  the  two  walls  allowed  the  puddle 
to  flow  around  them  and  close  up  much  better  than  if  the  braces  were  square 
timbers. 

The  use  of  candle-wicking  between  the  staves  proved  successful  at  Fort 
Madison,  and  calking  is  very  often  resorted  to  at  the  first,  and  also  to 
close  up  local  leaks.  The  use  of  this  and  the  use  of  a  stiff  grease  between 
the  layers  of  a  crib  will  be  referred  to  in  another  part  of  this  article. 

Th.e  use  of  tarpaulins  to  make  a  watertight  piece  of  work  is  described  in 
the  Trans.  Am.  Soc.  C.  E.,  Vol.  31,  by  Montgomery  Meigs,  engineer  in 
charge  of  the  government  work  at  Keokuk,  Iowa.  "The  upper  one  of  three 
locks  was  twice  repaired  by  separating  it  from  the  river  by  an  ordinary  plank 
and  mud  coffer-dam.  But  as  this  work  had  to  be  done  after  the  close  of 
navigation,  it  was  found  to  be  very  unsatisfactory  on  account  of  the  freezing 
of  the  puddle,  and  on  one  occasion  the  partly  puddled  dam  froze  and  upset. 
After  this  experience  it  was  determined  to  use  some  other  method  than 
puddle  to  produce  tightness.  There  was  available  for  drainage  a  50-H.  P. 
suction  dredge,  with  14-inch  suction,  and  a  rotary  Van  Wie  pump,  and 
plenty  of  12-inch  discharge  pipe  mounted  on  pontoons.  It  was  proposed  to 
drain  the  lock  with  this  dredge,  allowing  the  boat  to  settle  in  the  mud  at  the 
bottom  of  the  lock  as  the  water  left  it,  and  to  complete  the  work  with  a  3- 
inch  discharge  Pulsometer.  The  lock  being  350  feet  long  and  80  feet  wide, 
a  flat  place  on  the  bottom  was  selected,  the  dredge  placed  over  it  and  the 
necessary  length  of  discharge  pipe  placed  in  position  on  its  pontoons.  The 
point  selected  for  a  bulkhead  (Figs.  18  and  19)  was  just  outside  the  lock 
gates,  about  forty  feet  below  the  lower  mitre  sill,  where  there  was  a  smooth 
rock  bottom,  the  ends  of  the  dam  abutting  against  the  flaring  ashlar  wing 
walls  of  the  lock  approach. 

"The  bulkhead  was  constructed  with  thirteen  bents  eight  feet  apart,  of  the 
size  timber  shown,  with  light  diagonal  bracing.  After  being  built  2^  miles 
from  the  lock  it  was  towed  to  position  and  sunk  by  weighting  it  with  old 
railroad  rails,  enough  being  used  to  overcome  the  buoyancy  after  the  sheath- 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  3  I 

ing  was  added.  A  diver  was  employed  to  see  that  the  bottom  was  clear  of 
obstructions  and  to  guide  the  bulkhead  to  a  solid  bearing.  The  sheathing 
was  also  guided  to  place  by  his  assistance. 

"The  canvas  sheet,  which  was  designed  to  give  tightness  to  the  apron, 
was  of  two  breadths  of  ten  feet  and  one  breadth  of  six  feet  wide,  sewed 
together  edge  to  edge  for  convenience,  and  about  four  feet  longer  than  the 


^^;^vy^^ 

,-,  £      ^^o     tvjw  •'• 

Section     /• 


-  '  ^-^  '  •"          ~  ~        "'""" 


FIG.  18. — DETAILS  OF  CANVAS  AND  PLANK  BULKHEAD. 

extreme  length  of  the  apron.  Some  old  j^-inch  and  ^6-inch  chain  was 
sewed  to  one  edge  continuously  to  act  as  a  sinker  and  insure  the  lower  edge 
of  the  canvas  sheet  hugging  the  bottom  tightly.  A  few  stones  laid  on  it 
would  have  answered  the  same  purpose,  but  not  so  well.  The  canvas  was 
12-otince  duck. 


32  THE   COFFER-DAM  PROCESS  FOR   PIERS. 

"The  sheet  was  spread  under  water  by  the  diver.  It  lapped  on  the  bot- 
tom about  twelve  inches,  covered  the  face  of  the  apron  and  extended  some 
inches  up  the  face  of  the  wing  walls  at  the  end  of  the  dam.  Cleats  were 
nailed  on  the  angle  between  the  apron  and  the  wing  walls.  These  were  of 
Ix4-inch  strips,  nailed  with  2-inch  wire  nails  about  twelve  inches  apart.  The 
upper  edge  of  the  canvas  was  also  lightly  cleated  to  the  planking  in  a  similar 
manner.  No  other  nails  were  driven  in  the  canvas,  which  was  designed  to 
be  cut  up  into  tarpaulins  eventually.  Where  the  plank  touched  bottom  no 
beveling  was  used,  but  one  ragged  hole  was  stopped  with  the  beveled  "stop 
waters"  which  were  made  use  of.  The  dam  was  pumped  out  in  about  six 
hours  and  the  leakage  wras  so  small  that  a  3-inch  discharge  pulsometer  kept 
out  the  water,  and  was  then  run  only  at  intervals.  Small  leaks  were  stopped 
by  dumping  rotten  stable  manure  in  their  vicinity." 

It  is  interesting  to  note  that  the  bulkhead  stood  a  pressure  of  twelve 
feet  of  water.  Experiments  made  to  determine  what  pressure  12-ounce 
duck  would  stand,  show  that  the  clean  canvas  begins  to  leak  at  two  pounds 
pressure,  and  at  five  pounds  pressure  the  leakage  becomes  a  marked  amount. 
With  mud  on  the  canvass  the  leakage  becomes  noticeable  at  from  five  to 
seven  pounds,  and  of  a  considerable  amount  at  fifty  pounds  pressure,  these 
pressures  being  on  a  circle  4^  inches  in  diameter.  The  canvas  did  not 
rupture  at  800  pounds. 

The  suggestion  is  made  to  use  an  inverted  funnel  of  canvas  to  stop  the 
leakage  of  springs  on  rock  bottom.  (Fig.  20.)  The  canvas  to  be  spread  out 
over  the  bottom  and  weighted  down  with  concrete,  and  the  top  wired  to  a 
pipe  into  which  the  water  may  rise  until  the  pressure  head  is  overcome  or 
the  pipe  can  be  plugged.  Arrangements  of  this  nature,  but  without  the 
canvas  funnel,  have  been  frequently  used.  An  iron  pipe  set  on  end  is  fitted 
over  the  leak,  and  after  concreting  around  to  make  it  watertight,  the  water 
rises  inside  until  the  pressure  is  balanced.  A  watertight  wooden  box  may 
also  be  used  for  the  same  purpose. 

The  founding  of  a  new  inlet  tower  in  the  Mississippi  at  the  St.  Louis 
water  works  was  accomplished  by  using  a  coffer-dam  and  it  was  the  inten- 
tion to  form  a  junction  with  the  bottom  by  using  a  canvas  curtain.  When 
the  coffer-dam  was  floated  into  position  and  the  divers  were  sent  down  to 
spread  the  canvas  and  weight  it  down  with  stones,  it  was  found  to  be  dam- 
aged so  as  to  be  useless.  This  was  supposed  to  be  due  to  the  action  of  the 
swift  current,  but  was  most  probably  due  to  some  accident  such  as  fouling 
on  a  snag  or  against  a  barge. 

The  anchoring  of  the  crib  for  this  dam  is  related  in  the  Engineering 
News  of  July  4,  1891.  The  dam  was  to  be  located  near  the  head  of  a  stone 
dike  about  twenty  feet  in  height  and  on  solid  rock  bottom  which  was  uneven 
and  worn  into  grooves  by  the  action  of  the  current,  which  had  a  velocity  of 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  33 

between  six  and  eight  miles  per  hour.  The  bottom  was  leveled  off  by  blast- 
ing, to  receive  the  crib,  which  was  to  be  sunk  in  from  fifteen  to  eighteen 
feet  of  water. 

The  three  triangular  cribs  shown  (Fig.  21)  were  sunk  and  filled  with 
stone  and  were  used  to  hold  the  dam  in  place  while  building  and  while 
being  sunk.  Steel  cables  1%  inches  in  diameter  were  used  as  anchors. 

The  large  crib  also  served  as  a  protection  from  the  current  and  drift. 

The  size  of  the  crib  was  38x74  feet  outside  and  the  height  22  feet.  The 
12xl2-inch  yellow  pine  timbers  were  drift-bolted  together  with  from  one  to 
two  feet  spacing  of  bolts,  and  all  the  joints  between  the  timbers  were  calked. 
The  bracing  consisted  of  12-inch  square  timbers,  of  which  there  were  three 
rows,  the  braces  in  each  row  being  four  feet  apart  vertically.  These  were 
cut  out  as  the  masonry  was  built  up  and  bracing  against  the  stone  work  sub- 
stituted. 

There  were  four  sets  of  diagonal  bracing  as  shown.  The  space  between 
the  walls,  which  was  three  feet,  was  partly  filled  with  concrete  in  sacks,  and 
puddle  placed  on  top.  Sacks  of  clay  were  banked  up  around  the  outside, 
and  then  the  dam  wras  pumped  dry  with  a  10-inch  pump.  Inside  was  found 
eight  feet  of  mud  and  sixty  sacks  of  concrete  which  had  been  washed  there 
by  the  swift  current. 

The  amount  of  timber  used  was  125,000  feet,  B.  M.,  and  about  12,000 
feet  of  ^s-inch  round  iron  for  drift  bolts.  The  puddle  chamber  required 
1,000  sacks  of  concrete  and  1,00  barge  loads  of  clay,  while  10,000  sacks  were 
used  for  banking  up  clay  on  the  outside.  This  work  was  constructed  under 
the  direction  of  C.  V.  Mersereau,  Division  Engineer,  under  S.  B.  Russell, 
Principal  Assistant  Engineer. 

The  Queen's  bridge  at  Melbourne,  Australia,  is  a  plate  girder  structure, 
with  four  piers  of  eight  cylinders  each.  The  bottom  was  a  reef  of  bluestone 
which  had  been  shattered  by  blasting  and  which  was  silted  over  with  about 
three  feet  of  very  soft  silt. 

The  use  of  ordinary  puddle  coffer-dams  was  thought  to  be  too  expensive 
as  the  bridge  was  100  feet  in  width,  and  it  was  proposed  to  use  a  single  wall 
of  timber  protected  by  tarpaulins.  The  account  of  this  work  is  taken  from 
the  Engineering  News  of  April  4,  1895,  which  is  an  abstract  of  a  paper  by 
W.  R.  Renwick,  engineer  in  charge. 

To  insure  as  light  a  construction  as  possible  experiments  were  made  on 
the  strength  of  Oregon  pine,  and  it  was  found  that  tests  of  water  soaked  tim- 
ber showed  a  loss  of  strength  of  as  much  as  33  per  cent.,  when  compared  / 
with  tests  of  seasoned  timber.  The  break,  too,  of  the  water- soaked  pieces 
was  very  short.  This  strength  being  the  one  adopted,  a  very  low  factor  of 
safety  was  used.  A  separate  dam  was  constructed  around  each  tube,  but 
with  one  side  to  open  as  a  door  to  allow  its  removal  and  use  for  another 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  35 

place.  The  frame  was  made  from  12x12  Oregon  pine,  with  the  sticks  placed 
closer  together  near  the  bottom  to  resist  the  greater  water  pressure,  and  12x12 
pieces  were  run  up  the  corners,  the  frames  being  notched  in.  These  also 
served  as  spacers  for  the  side  timbers  and  as  door  frames.  The  sheeting  on 
the  outside  was  of  4x12  rough  timber,  and  outside  of  this  at  the  top  and 
bottom  were  wale  pieces,  6x12,  bolted  through  the  frames  with  1-inch  bolts 
to  hold  the  sheeting  in  place. 

The  tarpaulin  was  passed  completely  around  the  dam,  being  tacked  to 
the  waling  pieces,  and  so  arranged  as  to  allow  the  door  to  open. 

When  the  dam  had  been  placed  around  a  tube  the  sheeting  was  driven 
down  to  rock,  through  puddle  which  had  been  dumped  on  the  bottom,  and 


FIG.  20. — CANVAS  FUNNEL  FOR   CLOSING  LEAKS. 

the  pumping  was  readily  done  with  pulsometer  pumps.  The  only  serious 
leaking  was  where  the  1-inch  bolts  passed  through  the  joints  between  the 
sheeting,  but  these  were  plugged  with  soft  wood  plugs,  and  in  other  work 
the  bolts  were  flattened  to  three-eighths  of  an  inch  where  they  passed 
between  the  plank.  The  dams  were  removed  by  first  drawing  the  sheeting 
up  to  its  original  position,  when  the  door  was  opened  and  the  crib  taken  to 
another  tube.  The  depth  of  water  was  about  fifteen  feet,  but  while  this  was 
successful  in  this  instance,  the  method  should  not  be  copied  unless  the  condi- 
tions are  favorable,  nor  unless  the  cribs  are  made  practically  watertight  in 
themselves. 

This  was  the  case  in  the  above  work,  as  one  of  the  tarpaulins  was  acci- 
dentally torn  off  and  the  dam  still  excluded  the  water,  so  that  the  tarpaulin 
was  only  a  wise  precaution.  Why  the  cylinders  were  not  made  watertight 


36  THE  COFFER-DAM  PROCESS  FOR  PIERS. 

and  used  as  their  own  coffer-dam  is  not  stated,  but  this  possibly  could 
have  been  done. 

The  use  of  tarpaulin  in  closing  accidental  leaks  could  doubtless  be  made 
use  of  frequently,  but  as  the  sole  dependence  for  producing  tightness  it 
should  be  used  with  extreme  care,  in  a  gentle  current  and  well  protected 
from  damage. 

The  pivot  pier  of  the  Harlem  Ship  Canal  bridge  was  founded  in  a 
polygonal  coffer-dam,  from  the  plans  of  William  H.  Burr,  consulting  engi- 
neer. The  work  is  described  in  the  Engineering  Record  of  July  24,  1897: 
"The  rock  bottom  secured  by  the  canal  excavation  being  an  acceptable  sur- 
face for  the  masonry  of  the  pivot  pier  it  was  constructed  in  a  polygonal 


FIG.   21. — CRIBS   FOR   ANCHORING  ST.    LOUIS   COFFER-DAM. 

double- walled  coffer-dam  with  thirteen  sides  twenty-five  feet  high  and  sixty 
feet  in  extreme  diameter.  The  great  dimensions  of  the  coffer-dam  would 
have  made  it  difficult  to  build  and  launch  it  on  shore.  Consequently  it  was 
built  partly  on  a  detachable  raft.  As  shown  in  the  illustration  (Fig.  23)  the 
inside  wall  was  built  up  of  timbers  lapped  and  halved  at  the  angles;  the 
outer  wall  timbers  were  carefully  butt-jointed  and  secured  by  cross-struts 
and  1-inch  bolts  to  the  inside  walls.  The  rough-sawed  horizontal  surfaces 
of  the  inner  wall  were  bedded  in  stiff  grease  and  the  joints  calked,  which 
notably  resisted  the  penetration  of  the  water.  Each  course  of  timber  was 
secured  to  the  one  below  it  by  24 -inch  drift  bolts  spaced  about  four  feet 
apart.  When  the  bottom  was  thoroughly  cleaned  the  concrete  was  dumped 
in  place  by  a  special  steel  bucket.  Concreting  was  carried  on  night  and  day 


:J 

n    A     r 


o 


ZQ  Hd.  Bottom  to 
H.W. 


/2\IZ'-+*-6-/0'*U+*-J-8"x/Z-+ 
Drift  bolt,-,   j'x/8" 
about  3ft.a.pa.rt. 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


and  was  completed  before  puddling  was  begun.  Considerable  difficulty  was 
occasioned  by  the  irregularities  of  the  bottom  which  the  coffer-dam  could 
not  be  made  to  fit  closely.  Divers  were  sent  down  and  filled  in  bags  of  sand, 
as  at  S,  and  riprap  R  was  piled  up  outside  to  protect  it.  Then  the  space 
between  the  walls  was  filled  with  puddle." 

Another  polygonal  dam  was  constructed  for  the  draw  pier  of  the  Arthur 
Kill  bridge,  by  Alfred  P.  Boiler,  consulting  engineer.  The  following 
account  is  taken  from  Vol.  27  of  the  Transactions  Am.  Soc.  C.  E.:  "It  was 


Halt '(Section  Through  Pier  and  Co/ftrc/Q/n 


~K 


HALF  -"      C    ^      HALF    v 
ELEVATION.  SECTION. 


FIG.  22. — POLYGONAL    COFFER-DAM, 

HARLEM    SHIP-CANAL 

DRAW-BRIDGE. 


•   PLAN. 

FIG.  24.  — COFFER-DAM  FOR  PIVOT 
PIER    OF    THE    COTE  A  U 
BRIDGE. 


necessary  to  use  as  little  space  as  possible  for  the  dam,  and  to  construct  it 
without  interior  bracing,  so  that  a  double-walled  twelve-sided  polygon  (Fig. 
22)  with  walls  four  feet  apart  in  the  clear  was  used.  The  rock  bottom  was 
overlaid  with  two  feet  of  clay  and  the  clay  with  eighteen  inches  of  sand  and 
mud,  the  depth  of  water  over  the  rock  being  twenty-eight  feet  at  high  tide. 
The  square  hemlock  timbers  used  in  the  walls  were  halved  together  and  the 
walls  braced  together  by  bolts  and  round  timbers  for  struts,  the  round  tim- 
bers allowing  the  puddle  to  run  around  them  and  pack  well  as  thrown  in. 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  39 

Clamp  timbers  4x6,  in  two  lengths,  were  held  in  place  by  the  bolts  and  the 
struts  were  braced  against  6-inch  plank.  The  dam  was  built  to  one-third 
its  height  on  shore,  then  towed  to  position  and  built  up  until  grounded. 
Between  the  timbers  and  the  joints  candle-wicking  was  placed,  and  the 
courses  drift  bolted  together  every  three  feet  and  spiked  at  the  joints.  The 
rock  was  dredged  bare  before  placing  the  crib,  which  was  filled  with  a  hard, 
gravelly  clay  between  the  walls  after  being  sunk  in  place.  A  rich  Portland 
concrete  was  dumped  inside,  from  triangular  buckets,  to  seal  the  bottom 
and  then  the  dam  was  pumped  out  with  a  6-inch  pump  and  kept  dry  by 
pumping  at  intervals.  In  one  place  the  concrete  was  not  thick  enough  and 
a  spring  came  up  through  a  fissure  in  the  rock.  This  was  boxed  in  and  led 
to  the  sump.  The  material  used  was  140,000  feet  of  timber,  15,000  pounds 
of  iron,  and  600  yards  of  puddle." 

A  piece  of  work  similar  to  the  Canadian  Pacific  example  was  an  octag- 
onal single- walled  dam  used  in  the  construction  of  the  Coteau  bridge  on  the 
Canada  Atlantic  Railway.  This  is  illustrated  in  the  Engineering  'Nc-cs  of 
May  30,  1891  (Fig.  24),  and  was  braced  thoroughly  with  cross-timbers  built 
into  the  sides.  The  bottom  being  of  rock  it  was  partly  filled  with  concrete 
to  make  it  watertight. 

The  different  forms  of  sheet  piling  will  next  be  taken  up,  together  with 
pile  driving  machinery  and  the  methods  of  driving  both  sheet  and  guide 
piles.  After  this  will  be  described  the  use  of  sheet  piles  for  forming  water- 
tight coffer-dams,  by  reference  to  actual  constructions  of  that  character. 


ARTICLE   IV. 

THE    COFFER-DAM    PROCESS    FOR    PIERS.* 

PILE    DRIVING   AND   SHEET   PILES. 

N  no  department   of    engineering  have   ancient  methods  been  more  rigidly 
adhered  to  than  in   that  of  pile  driving.      The  form  of  the    pile-driver 
derrick  has  remained  so  characteristic  that  a  person  but  slightly  familiar 
with  the  subject  would  have  little  difficulty  in  recognizing  the  pile  driver 
in  the  picture  of  Caesar's  Bridge  (Fig.  3)  in  the  first  article.     The  bridge 
of  the  Emperor  Trajan  over  the  River  Danube  is  an  instance  of  the  early 
use  of  piles.     This  bridge  was  constructed  in  the  first  century,  and  when 
the  piles  under  water  were  examined  in  the  eighteenth  century  they  were 
found  in  some  cases  to  have  become  petrified  to  a  depth  of  three-fourths  of 
an  inch  from  the  surface,  beyond  which  the  timber  was  in  its  original  state. 
Before  derricks  were  used  it  is   probable  that  piles  were  driven  by  a  large 
maul  of  hard  wood,  which  is  termed  by  Cresy  a  "three-handed  beetle."    The 
block  of  hard  wood  was  hooped  with   iron  and  had  two  handles  radiating 
from  its  center,  to  be  worked  by  two  men,  while  a  third  man  assisted  in  lift- 
ing it  by  means  of  a  short  handle  opposite. 

Wooden  mauls  are  still  used  where  sheet  piling  is  to  be  driven  into  a  soft 
bottom,  and  heavy  iron  mauls  or  sledges  are  also  used;  but  as  has  been  fre- 
quently stated  such  a  soft  bottom  should  be  dredged  and  some  more  elab- 
orate apparatus  used  to  drive  the  piles  into  a  harder  substratum. 

The  most  primitive  form  of  the  pile-driving  derrick  is  similar  to  the  one 
used  in  1751  by  the  celebrated  French  engineer,  Perronet,  at  the  brdige  of 
Orleans  (Fig.  25).  This  was  arranged  with  a  number  of  small  ropes  splayed 
out  from  the  end  of  the  lead  line,  so  that  a  number  of  men  could  pull  down 
at  one  time,  the  drop  of  the  hammer,  of  course,  being  limited  by  the  reach 
of  the  men's  arms.  The  windlass  shown  was  for  the  purpose  of  raising  the 
pile  into  place  between  the  leads. 

The  same  engineer  improved  upon  this  derrick  by  adding  a  large  bull- 
wheel  to  the  windlass,  on  which  was  wound  a  rope  to  be  pulled  by  a  horse 
from  the  side,  as  shown  in  Fig.  26,  thus  winding  up  the  lead  line  on  the 

*  The  subject  of  pile-driving  has  been  restricted  to  the  ordinary  methods  and  operations  ; 
such  unusual  processes  as  gunpowder  pile  driving  and  the  like  have  not  been  .referred  to. 

Pile-driving,  with  the  assistance  of  the  water- jet,  has  been  described  on  page  70,  in  the 
account  of  the  Sandy  Lake  coffer-dam.  The  ordinary  operations  of  pile-driving,  as  practiced 
on  that  work,  are  also  described  in  some  detail. 

40 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


windlass.  This  same  apparatus  is  in  use  down  to  the  present  time,  except 
that  one  seen  recently  had  the  windlass  at  right  angles  to  the  one  illustrated. 

The  ram  or  Hammer  used  in  olden  times  was  of  oak,  bound  with  iron, 
and  weighed  for  the  work  at  Orleans  1,200  pounds  for  the  main  piles  which 
were  nine  to  twelve  inches  in  diameter  and  which  were  driven  three  to  four 
feet  apart,  center  to  center,  to  a  depth  of  six  feet  into  the  bed  of  the  river; 
the  ram  for  the  sheet  piles  only  weighed  half  as  much,  the  sheet  piles  being 
about  twelve  inches  wide  by  four  inches  thick. 

At  the  bridge  of  Saurnur,  which  was   built   about  the  year    1756,   De 


FIG.  2o.— PERRONET'S   PILE 
DRIVER. 


FIG.  26.— PERRONET'S   BULL   WHEEL 
PILE   DRIVER. 


Cessart  employed  a  driver  with  a  bull-wheel, in  the  periphery  of  which  were 
set  pins,  to  form  handles  for  the  men  to  pull  upon  and  rotate  the  wheel. 
Eight  men,  by  making  three  turns  of  the  wheel,  raised  the  ram  weighing 
1,500  pounds  six  feet,  when  it  was  unhooked  and  allowed  to  drop.  The  piles 
cost  from  two  to  five  dollars  each  in  place. 

A  very  simple  form  of  pile  driver  is  shown  in  Fig.  27  and  was  described 
in  the  Engineering  News  of  March  16, 
1893,  by  Julian  A.  Hall.  The  hammer 
is  hewed  out  of  a  section  of  a  hardwood 
log,  and  has  pieces  bolted  on  the  sides  to 
hold  it  in  the  leads,  which  should  give 
plenty  of  clearance.  The  derrick  was 
constructed  of  very  light  timber,  the  ver- 
ticals being  4-inch  sawed  stuff  and  the 
bottom  timbers  6x6  inches.  The  rope 
passes  over  the  sheave  A  and  down  over 
the  tops  of  the  steps  B  B,  on  which  the 

men  stand  to  pull  the  line  and  thus  operate  the  hammer.  This  was  a  very 
inexpensive  apparatus  and  was  found  to  work  well.  Where  there  is  already 
in  use  a  heavier  hammer  of  cast  iron  it  can  be  used  by  striking  light 


FIG.    27.— SHEET   PILE   DRIVER. 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


blows.  The  construction  of  the  ordinary  pile  driver  derrick  is  a  simple 
piece  of  framing,  when  good  straight  timber  is  easily  obtained,  the  essential 
features  being  to  keep  the  leads  free  from  any  obstruction  for  the  hammer  and 
to  have  efficient  bracing. 

For  bracing  a  derrick  under  twenty-five  feet  a  straight-back  brace  or 


FIG.  28. — PILE   DRIVER    DERRICK    FOR    USE    ON    A    SCOW. 

ladder  having  two  horizontals  running  to  the  leads,  and  two  side-braces  will 
be  sufficient.  But  for  a  higher  one,  either  additional  long  braces  should  be 
used  or  diagonals  introduced  between  the  leads  and  the  ladder.  The  use  of 
long  braces  is  shown  in  Fig.  28,  which  is  the  design  of  pile-driver  such  as  is 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


43 


FIG.     29.—  LIDGER- 
\VOOD  PILE  DRIV- 
ING  DERRICK. 


used  about  harbors  or  rivers  on  heavy  work.  It  would  be  mounted  on  a  scow 
or  flat-boat  sixty  feet  in  length,  twenty-five  feet  in  width  and  of  about  six 
feet  in  depth.  The  design  of  smaller  derricks  can  be 
approximated  from  this  one,  the  bracing  being  used  in 
proportion. 

It  will  be  noticed  that  the  guides  for  the  hammer 
are  4x4  inches  lined  with  a  steel  plate.  Two  lines  are 
provided,  one  being  for  the  operation  of  the  hammer  and 
the  other  for  pulling  piles  into  place.  Especial  attention 
is  called  to  the  hooks  at  A,  as  these  are  seldom  shown  in 
the  plan  of  a  derrick  and  they  are  of  constant  use  for 
clamping  and  guiding  piles.  A  timber  laid  across  is 
wedged  tight  against  the  pile  to  draw  it  to  line,  and  can 
be  used  to  correct  a  stick  which  is  beginning  to  slant 
badly.  Similar  clamps  of  course  are  used  on  the  oppo- 
site side  of  the  leads. 

Where  a  pile  begins  to  sliver  or  split  in  driving,  if 
the  sliver  is  spiked  down  and  the  clamps  used  to  hold  it  in 
place,  the  trouble  can  usually  be  corrected  before  the  pile  is  badly  damaged. 
The  use  of  diagonal  bracing  between  the  leads  and  ladder  is  shown  in  the 
Lidgerwood  derrick  (Fig.  29)  in  which  a  diagonal  is  introduced  between  each 
pair  of  horizontals.  This  form  of  bracing  is  very  satisfactory  and  equally  as 
good  as  the  other  method.  The  diagonals  on  a  very  large  driver  may  be 
extended  over  two  panels  and  planks  spiked  down  to  the  horizontals  to  form 
a  platform  for  the  workmen.  In  smaller  derricks  the  diagonal  bracing  is 
most  always  omitted,  dependence  being  placed  in  the  stiffness  of  the  leads 
and  the  bracing  from  the  ladder  and  horizontals,  as  was 
done  in  the  derrick  shown  in  Fig.  4. 

The  power  for  driving  with  a  small  hammer  weighing 
from  500  to  1,500  pounds,  may  be  furnished  by  laborers 
pulling,  but  this  is  a  slow  operation  and  horse  power  is 
nearly  always  used  where  steam  is  not  available.  The 
power  is  furnished  from  a  drum  with  a  long  lever,  to  which 
the  horse  is  hitched  and  winds  up  the  hammer  by  walking 
in  a  circle  about  the  drum,  the  frame  of  which  is  firmly 
fastened  in  place.  This  is  called  a  "horsepower"  apparatus 
and  works  slowly,  but  is  a  cheap  and  satisfactor}7  way 
where  a  very  few  piles  are  to  be  driven.  To  the  hammer 
line  are  attached  the  tongs  or  nippers,  which  engage  the  pin  in  the  top  of 
the  hammer  (Fig.  30),  and  when  the  hammer  has  reached  the  proper 
height  it  is  dropped  by  pulling  a  tripping  rope  and  releasing  the  tongs,  or  if 
the  hammer  is  hoisted  to  the  top  of  the  leads,  the  top  arms  of  the  tongs  are 


FIG.  30.— HAM- 
MER WITH 
NIPPERS. 


44 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


pushed  together  by  the  wedges  on  the  leads  and  the  hammer  released  auto- 
matically. This  is  a  slow  method  on  account  of  waiting  until  the  tongs  run 
down  again  and  engage  the  hammer.  The  horse  power,  of  course,  has  a 
ratchet,  so  that  the  rope  runs  down  free  and  usually  the  blows  are  hurried 
by  overhauling  the  line.  With  the  addition  of  a  hoisting  engine  all  this  is 
changed  and  pile  driving  becomes  one  of  the  most  stirring  operations  of 
the  contractor.  When  the  hammer  is  hoisted  up,  the  friction  lever  is  released 
and  the  hammer  descends  carrying  the  rope  with  it,  as  the  tongs  are  done 


FIG.    31. — PILE   DRIVING    SCOW,  NEW   YORK   STATE    CANALS. 

away  with  and  the  line  attached  directly  to  the  hammer.  A  good  engine 
man  will  catch  the  hammer  on  the  rebound  and  materially  lessen  the  time 
between  the  blows  and  likewise  the  cost  of  driving. 

With  a  heavy  hammer  shorter  drops  are  made,  thus  causing  much  less 
damage  to  the  pile,  which  would  split  badly  under  the  high  drop  from  the 
use  of  tongs.  For  the  smaller-sized  hammers — from  1,000  to  1,500  pounds — 
an  engine  of  10-horse  power  is  mostly  used,  as  it  is  usually  thought  best  to 
have  a  surplus  of  power  in  case  ol  need;  while  for  a  3,000  pound  hammer  a 
20-horse-power  engine  would  likely  prove  the  best  and  most  economical,  but 
not  infrequently  a  25-horse-power  hoist  is  employed. 

The  cost  of  an  outfit  will  vary  greatly  and  the  only  satisfactory  way  is  to 
get  prices  from  responsible  firms,  but  for  preliminary  estimates  the  cost  of  a 
10-horse-power  hoist  with  single  cylinder  and  single  drum  may  be  taken  at 
about  $900,  and  for  a  20-horse  power  at  $1,270.  Preliminary  prices  for  other 


THE   COFFER-DAM  PROCESS  FOR   PIERS. 


45 


sizes  of  single  cylinder,   single    drum  hoists,  may    be   obtained    from  the 
formula: 

Cost  =i/81,000xhorse  power. 

The  double  cylinder  engines  will  cost  about  10  per  cent,  more  and  double 
drums  about  10  per  cent,  additional  to  this. 

Pile  driver   derricks  will    vary  much   in  cost  owing  to  the  location,  on 
account  of  the  cost  of  timber,  but  a  minimum  cost  for  a  first-class  derrick 
will    be   $6    per    vertical  foot   and  a   maximum  of  $8. 
Being  such  a  simple  structure  the  easiest  and  safest  way 
will  be  to  make  an  estimate  for  each  case. 

In  the  selection  of  an  engine  it  is  well  to  remember 
that  with  a  double  drum  a  second  pile  may  be  hoisted 
into  place,  while  the  first  one  is  being  driven,  as  all  der- 
ricks are,  or  should  be,  provided  with  two  sheave  wheels 
at  the  top  for  this  purpose.  While  a  single-drum  engine 
has  a  spool  for  this  purpose,  it  cannot  be  used  very  satis- 
factorily. 

A  pile  driver  on  a  scow  is  shown  in  Fig.  31,  such  as 
was  used  in  driving  piles  on  the  New  York  State  canals. 
Another  pile  is  just  being  hoisted  into  position.  The 
hoisting  engine  has  no  protection,  but  a  shed  or  house 
is  mostly  provided  as  a  protection  from  the  weather. 

While  little  change  has  ever  been  effected  in  the  de- 
sign of  pile  driving  derricks,  the  adoption  of  steam  hoists 
was  a  great  improvement,  as  \vas  also  the  invention  of 
the  steam  pile  hammer  by  James  Nasmyth.  The  principle 
is  the  same  as  that  of  steam  forging  hammers,  and  was 
applied  by  Nasmyth  to  pile  driving  in  1845,  the  ham- 
mers of  this  class  bearing  his  name  to-day.  His  idea 
was  that  the  drop-hammer  was  calculated  more  for  de- 
struction than  for  useful  effect  and  he  termed  it  the 
"artillery  or  cannon  ball  principle."  Besides  this  the 
action  of  the  drop-hammer  even  with  the  use  of  the 
"monkey"  engine  was  somewhat  slow. 

Samuel  Smiles  says  that  "in  Xasmyth's  new  and 
beautiful  machine  he  applied  the  elastic  force  of  steam 
in  raising  the  ram  or  driving-block,  on  which,  the  driv- 
ing-block being  disengaged,  its  whole  weight  of  three 
tons  descended  on  the  head  of  the  pile,  and  the  process  being  repeated  eighty 
times  in  a  minute  the  pile  was  sent  home  with  a  rapidity  that  was  quite 
marvelous  as  compared  with  the  old  method.  In  forming  coffer-dams  for 
piers  and  abutments  of  bridges,  quays  and  harbors,  and  in  piling  the  foun- 


FIG.  32. — WARRING- 
TON  -  NASMYTH 
STEAM  PILE 
HAMMER. 


46 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


dations  of  all  kinds  of  masonry  the  steam  pile  driver  was  found  of  invalua- 
ble use  by  the  engineer.  At  the  first  experiment  made  with  the  machine 
Mr.  Nasmyth  drove  a  14-inch  pile  fifteen  feet  into  hard  ground  at  the  rate  of 
sixty-five  blows  per  minute.  The  saving  of  time  effected  by  this  machine 
was  very  remarkable,  the  ratio  being  as  1  to  1,800;  that  is,  a  pile  could  be 
driven  in  four  minutes  that  had  before  required  a  day.  One  of  the  peculiar 
features  of  the  invention  was  that  of  employing  the  pile  itself  as  the  support 
of  the  steam  hammer  part  of  the  apparatus  while  it  was  being  driven,  so  that 


FIG.  33. — WARRINGTON-NASMYTH   HAMMER,    FAIR   HAVEN   BRIDGE. 

the  pile  had  the  percussive  force  of  the  deadweight  of  the  hammer  as  well  as 
the  lively  blows  to  induce  it  to  sink  into  the  ground.  One  of  the  most 
ingenious  contrivances  of  the  pile  driver  was  the  use  of  steam  as  a  buffer  in 
the  upper  part  of  the  cylinder,  which  had  the  effect  of  a  recoil  spring  and 
greatly  enhanced  the  effect  of  the  downward  blow." 

Many  modifications  of  this  hammer  have  been  manufactured,  and  one 
much  used  at  present  is  the  Warrington-Nasmyth  hammer,  made  by  the 
Vulcan  Iron  Works.  This  hammer  (Fig.  32)  is  made  in  three  sizes, 
the  weight  of  the  striking  parts  being  550  pounds  for  sheet  pile  work,  3,000 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


47 


FIG.  34. — CRAM-NASMYTH    STEAM    PILE   HAMMER. 

pounds  for  medium  pile  work,  and  4,800  pounds  for  use  on  heavy  work. 
This  machine  is  provided  with  a  positive  valve-gear,  a  short  steam  passage 
to  avoid  the  waste  of  steam,  a  wide  exhaust  opening  to  prevent  back  pres- 
sure as  the  hammer  drops,  a  piston-head  forged  on  the  rod,  and  channel  bars 
on  the  sides  to  allow  the  pile  to  be  driven  lower  than  the  leads  of  the  derrick. 
The  hammer  is  attached  to  the  hoist  rope,  but  this  is  left  slack  when  the 
hammer  is  resting  on  the  head  of  the  pile,  steam  is  turned  on  and  the  ham- 


48 


THE   COFFER-DAM  PROCESS  FOR   PIERS. 


mer  pounds  automatically  at  the  rate  of  sixty  to  seventy  blows  per  minute 
until  the  pile  is  driven.  The  bottom  casting  which  rests  on  the  pile  is  a 
bonnet  which  encases  the  top  and  prevents  brooming  or  splitting. 

The  hammer  should  have  plenty  of  play  in  the  leads,  and  the  steam  pipe 
should   extend  half  way  up  the  derrick  to    save    length  of  hose.       This 


FIG.  35. — MACHINE    FOR    SAWING    OFF    PILES   UNDER    WATER. 

hammer  has  a  record  of  as  high  as  seventy-five  to  one  hundred  piles  per  day, 
and  one  account  gives  the  record  of  3,UOO  lineal  feet  of  piling  per  day  at  a 
cost  of  $50,  the  number  of  men  employed  being  sixteen  and  the  coal  con- 
sumption one  ton.  This  hammer  is  shown  in  Fig.  33  in  use  driving  piles  for 
bridge  work  on  the  Fair  Haven  bridge. 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  49 

Another  form  of  the  Nasmyth  hammer  is  the  Cram  (Fig.  34)  which  is 
very  simple  in  construction.  The  driving  head  is  hollow  and  the  steam 
enters  through  a  hollow  piston  rod,  causing  the  head  or  cylinder  to  rise  on 
the  rod.  Four  sizes  are  made,  with  hammers  of  430  pounds,  2,000  pounds, 
3,000  pounds  and  5,500  pounds.  The  small  hammer  which  is  listed  at  $300 
is  used  for  sheet  pile  work  by  inserting  a  "follower"  of  oak  which  fits  the 
base  or  pile  cap,  and  which  has  a  slit  in  the  lower  end  to  fit  the  sheet  pile. 
The  number  of  blows  per  minute  is  the  same  as  other  steam  pile  hammers 
and  an  average  of  eighty-three  piles  per  day  of  ten  hours  is  reported,  where 
they  were  driven  seventeen  feet  into  sand  and  oyster  shells  in  the  Passaic 
river,  the  largest  day's  work  being  121  piles,  or  nearly  double  the  best  work 
with  an  ordinary  hammer. 

Mention  has  been  made  of  the  use  of  a  rock  drill  as  a  Nasmyth  hammer, 
on  the  Great  Kanawah  river  coffer-dams;  and  where  any  amount  of  driving 
is  to  be  done  it  will  certainly  be  wise  to  use  a  hammer  of  the  Nasmyth  type. 


FIF.  36. — PILE-PULING    LEVER.      AFTER  CRESY. 

The  guide  piles  of  a  coffer-dam  should  always  be  driven  with  the  idea  of 
using  them  as  a  support  for  pumps,  engines,  derricks,  and  the  like, 
although  it  will  often  be  found  cheaper  to  rig  up  on  flat-boats  when  there  is 
danger  from  floods.  In  determining  what  load  a  pile  will  carry  from  this 
source,  or  when  driven  as  a  foundation  pile  to  support  the  masonry,  Wel- 
lington's formula  is  at  once  the  most  accurate  and  the  easiest  to  remember 
and  use.  For  a  drop-hammer,  multiply  twice  the  weight  of  the  hammer  in 
pounds  by  the  drop  in  feet  and  divide  by  the  last  sinking  in  inches  plus  one, 
and  the  result  is  t  he  load  in  pounds  the  pile  will  carry,  with  a  factor  of  six 
for  safety.  This  is  easily  remembered  as  2  wh  over  s  +  1,  and  is  always 
ready  for  use.  For  the  steam-hammer  the  form  is  2  wh  over  s+0.1,  the 
"wh"  representing  the  dynamic  effect  of  the  hammer. 

Where  piles  have  been  firmly  driven  and  they  are  to  be  removed  when 
the  work  is  done  they  can  be  cut  off  under  the  water  by  a  machine  similar  to 
Fig.  35,  which  can  be  operated  from  a  barge.  The  description  in  the  Engi- 
neering News  gives  but  little  information  in  addition  to  the  drawing.  The 
shaft  works  in  cast-iron  sleeves  attached  to  a  timber,  which  slides  in  the 


50  THE  COFFER-DAM  PROCESS  FOR  PIERS. 

leads,  this  being  operated  by  the  winch  shown  in  side  elevation.  The  final 
adjustment  is  made  by  the  hand- wheel  on  the  3-feet  adjusting  screw. 
Where  the  piles  are  not  so  solidly  driven  they  can  be  pulled  out  with  a  lever, 
an  old  form  of  which  is  given  by  Cresy  (Fig.  36).  In  place  of  the  pin  and 
links,  a  chain  closely  wrapped  around  the  top  of  the  pile  is  usually  made 
use  of. 

The  apparatus  used  on  the  New  York  State  canal  work  (Fig.  37)  con- 
sisted of  a  strong  frame  mounted  on  a  scow,  from  which  was  suspended  a 
\eavy  set  of  falls  to  attach  to  the  chain  wrapped  around  the  head  of  the  pile, 
f  he  pulling  was  done  by  an  engine  placed  on  the  scow. 

The  construction  of  coffer-dams  with  sheet  piling  has  led  to  the  use  of  a 


FIG.  37.— PII,E-PUI,IJNG   SCOW,    NEW  YORK   STATE   CANALS. 

number  of  forms  of  sheet  piles,  some  of  which  are  driven  only  as  a  protection 
to  the  puddle,  while  others  are  nearly  or  quite  watertight  in  themselves. 
The  principal  forms  are  shown  in  Fig.  38,  the  simplest  form  being  plarik  of 
some  considerable  thickness  (a)  for  which  Stevenson  specified  4^  inches  by 
not  exceeding  9  inches  in  width  for  the  Hutcheson  bridge.  The  points  are 
sharpened  as  at  (i)  so  they  will  draw  together  in  driving,  and  as  at  (j)  to 
cause  them  to  drive  straight  and  easy.  The  same  principle  is  embodied  in 
the  patent  metal  point  shown  at  (k),  which  is  used  to  protect  the  point  when 
driving  through  coarse  gravel. 

The  piles  at  Buda-Pesth  were  increased  to  fifteen  inches  square  in  order 
to  resist  the  pressure  brought  upon  the  sides  of  the  dam  by  the  puddle,  the 
water,  and  also  by  the  ice.  Flat  plank  are  also  used  by  driving  two  or  more 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


rows  as  at  (b),.  the  second  and  third  rows  being  used  to  close  the  cracks  in 
the  main  row  of  piles  and  retain  the  puddle.  An  example  of  this  will  be 
given  in  the  next  article,  where  it  was  used  on  the  Michigan  Central  Railway. 
The  extra  rows  may  be  of  thinner  plank  if  they  can  be  driven. 

Mention  has  already  been  made,  incidentally,  of  the  use  of  V-shaped 
tongue  and  groove  piling  (c),  on  the  Union  Pacific  Railway.     This  may  be 


I      .       I      "A 


V 


FIG.  38. — SHEET  PII.ES  AND  SHEET  PILE  DETAILS. 

made  on  a  beveled  saw  table,  the  saw  cutting  half  through  the  plank  from 
opposite  sides  at  each  cut.  This  will  produce  a  reasonably  tight  wall,  if 
care  is  used  in  driving  and  if  the  points  are  sharpened  to  draw  them  together 
and  make  tight  joints. 

Ordinary  tongue  and  groove  piling  (d)  is  frequently  used,  but  a  more 
frequent  form  is  that  shown  at  (e),  like  that  used  on  the  Robinson  circular 
dam.  The  two  pieces  forming  the  groove  and  the  piece  for  the  tongue  are 


THE  COFFER-DAM.  PROCESS  FOR  PIERS. 


FIG.    39; — CHARLESTOWN    BRIDGE.      DRIVING    WAKEFIEI.D    SHEET    PII.ING. 

spiked  to  the  9x12  with  6-inch  spikes  sloping  upward.  A  sheet  pile  dam 
on  another  pier  of  the  Arthur  Kill  bridge,  employed  piling  in  which  the 
grooves  were  made  by  making  two  saw  cuts  and  cleaning  out  between  with  a 
chisel,  the  tongue  being  formed  in  the  same  manner  as  at  (f),  the  tongue 
being  spiked  in  one  side. 

A  method  which  is  not  often  employed  is  shown  at  (f)  two  grooves  being 
made  in  the  sheet  pile  and  a  key  driven  after  the  piles  are  down.  Should 
the  piles  not  drive  in  perfect  line,  and  the  groove  fail  to  match,  the  method 
will  not  be  found  to  be  a  success. 

Sheet  piling  formed  of  two  or  more  plank  bolted  together  is  being  exten- 
tively  used,  one  of  them  (g)  being  formed  by  two  planks  sawed  with  beveled 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  S3 

edges  and  bolted  together  to  form  a  pile  similar  to  (c).  This  forms  a  pile 
which  will  drive  easily  on  account  of  having  some  size  and  which  will 
require  fewer  supports  in  the  shape  of  waling  pieces. 

Several  examples  already  given  describe  the  use  of  Wakefield  patent 
sheet  piling  (h),  the  method  of  sharpening  being  shown  at  (h').  This  is 
constructed  of  three  layers  of  plank  from  one  to  four  inches  thick,  owing  to 
the  pressure  to  be  sustained.  The  center  plank  must  be  sized  to  keep  the 
tongue  and  groove  uniform,  and  the  plank  are  bolted  together  with  six  bolts 
for  a  length  of  from  sixteen  to  twenty  feet,  two  bolts  near  each  end  and  two 
intermediate.  For  long  piles,  spikes  should  be  driven  between  the  bolts. 
The  bolts  vary  from  f  inch  for  1-inch  plank  to  3^-inch  for  4-inch  plank.  A 
coffer-dam  constructed  with  this  piling  is  shown  in  process  of  construction 
in  Fig.  39,  for  the  foundations  of  Charlestown  bridge  near  Boston.  A 
description  of  this  will  be  given  in  the  next  article. 

Pile  shoes  for  use  on  round  or  square  piles  are  shown  at  (1)  and  (m),  (1) 
being  patent  forms.  Straps  of  bar  iron  are  used  in  many  cases  with  suc- 
cess, for  main  piles,  and  sheet  iron  of  J/i -inch  thickness,  bent  to  a  "V"  and 
spiked  on,  is  often  all  that  is  necessary  when  shoes  must  be  used  on  sheet 
piles. 

The  thickness  of  sheet  piling  should  be  sufficient  to  prevent  the  plank 
from  bulging  and  should  be  calculated  to  stand  a  water  pressure  due  to  the 
depth,  and  for  a  span  equal  to  the  distance  between  the  waling  timbers  or 
other  supports.  This  would  necessitate  wales  every  six  feet  for  3-inch 
plank  under  five  feet  head,  or  wales  every  three  feet  for  a  21-feet  head. 
Plank  4y2  inches  thick  would  require  wales  every  seven  feet  under  a  9-feet 
head,  or  every  five  feet  for  an  18-feet  head.  Timbers  nine  inches  thick  will 
carry  nine  feet  under  a  20-feet  head,  while  the  15-inch  timbers  of  the  Buda- 
Pesth  dam  would  carry  twelve  feet  under  a  33-feet  head. 

Good  timber  should  always  be  employed  if  it  can  be  procured,  or  if  faulty 
stuff  must  be  used,  allowance  must  be  made  by  using  thicker  piles  and  by 
placing  the  wales  closer  together. 


It 

I**«LT? 


ARTICLE   V. 

THE    COFFER-DAM    PROCESS    FOR    PIERS.* 

CONSTRUCTION   WITH   SHEET   PILES. 


ATER  pressure  against  the  sides  of  a  sheet  pile  coffer-dam  is 
seldom  provided  for  in  an  accurate  manner,  the  thickness  of 
the  piling  being  usually  decided  upon  from  past  experience,  as 
is  also  the  size  and  spacing  of  the  guide  piles  and  wales. 

«£&£--      ,  These  are  points  where  guess-work  should  be  eliminated,  as 

otherwise  good   coffer-dams  are  often  seen,  where  the  pressure 

has  so  bulged  the  plank  as  to  cause  leakage.      While  this  may  perhaps  be 

corrected  by  additional  bracing,  simple  calculations  may  easily  be  made  to 

determine  the  size  beforehand. 

The  pressure  against  a  coffer-dam  may  act  as  at  (a),  Fig.  40,  the  sheet 
piling  being  in  the  condition  of  a  beam  fixed  at  one  end  and  loaded  with  a 
gradually  increasing  weight,  as  shown  by  the  dotted  lines,  due  to  the 
pressure  of  water  or  puddle  at  62  .4  pounds  per  cubic  foot.  Then  the  load  on  a 
width  w  of  the  wall  is  124.  8  w  d2  and  the  moment  of  the  pressure  is  83.  2  zv  d*  . 
Taking  the  allowable  unit  stress  on  wet  timber  at  1,000  pounds  per  square 
inch,  the  thickness  /  of  the  sheet  piling  may  be  obtained  from  the  formula 


in  which  d  is  to  be  taken  in  feet  and  the  resulting  value  of  /  will  be  the 
thickness  in  inches  of  the  sheet  piling. 

This  formula  has  been  expressed  in  a  graphic  manner  in  diagram  (d), 
Fig.  40,  from  which,  knowing  the  depth  of  water  2d,  the  thickness  of  piling 
may  be  read  directly  without  calculation. 

The  addition  of  a  strut,  as  at  (b),  Fig:  40,  places  the  sheet  piling  in  the 
condition  of  L  beam  supported  at  the  upper  end  and  fixed  at  the  lower  end, 
but  for  practical  reasons,  it  is  best  to  consider  it  as  merely  supported  at  both 
ends.  The  load  will  be  the  same  as  in  the  former  case,  124.8  w  d2  ,  but  the 

*  The  assumption  that  the  pressure  of  puddle  will  be  the  same  as  water-pressure  is  made 
advisedly.  It  is  true  that  very  wet  clay,  approaching  a  fluid  condition,  will  exert  a  much 
greater  pressure,  but  it  would  then  be  useless  as  puddle.  Dry  clay  would  exert  a  pressure 
of  less  than  half  that  due  to  water,  so  it  has  been  assumed  that  wet  clay  or  puddle  would 
exert  the  same  force  as  water.  Should  it  exceed  it  for  a  short  time  no  damage  would  be 
done,  owing  to  the  low  unit-stress  adopted. 

54 


55 


/0 


4o 


3      4      5     *6     ?.       5      9      /o 

77i/c /r/\  e^5  Piling  m  lr\ct\ e5 . 

&ZE  PlL  //V <5 .  blA  GRA  A]    (a ). 


f.     *«>. 


P/Z.  IHG.blA  GRA  MS  (btc). 


W 


$35 

30 


60 


In 


Q  O  O 


§  5 


3*t56?$9/0  ^  »rv<r-^'o 

(f)  bbfance  Between  lVc?/e5  /A  Feet .       (ti)Po\iMi$  Per  Square  /ncA  Allowabk, 
(VALE5  FOP  ffFT.  cJP/4/V.  TlMBEP  OTPUT3  -  IVE7 


FIG.    40. — ARRANGKMENT    AND    DIAGRAMS    OF    SIZES    FOR    SIIEKT-1'ILK    COFFER-DAMS. 


56  THE   COFFER-DAM  PROCESS  FOR  PIERS. 

maximum  moment  will  occur  at  a  point  x  which  is  a  distance  from  the  top 
equal  to  1.16  times  d,  and  has  a  value  of  32  iv  d3.  The  thickness  t  may  be 
found  from  the  formula 


When  the  section  of  the  plank  to  be  calculated  is  located  as  '  V  in  (c) 
of  Fig.  40,  it  is  in  the  condition  of  a  beam  fixed  at  both  ends  and  loaded  with 
a  uniform  load  m  and  a  triangular  load  n.  The  exact  analysis  of  this  is  too 
lengthy  to  be  taken  up  here,  and  reference  may  be  made  to  page  195  of 
"Wood's  Resistance  of  Materials." 

For  practical  purposes  we  may  consider  the  load  as  all  uniform  and  due 
to  the  head  acting  at  the  middle  of  the  span.  This  will  give  a  load  of 
62.4  TV  d  s  on  the  span  5  for  a  width  ivy  and  a  moment  of  7.8  d  52,  which 
gives  a  formula  for  practical  use,  for  a  unit  stress  of  1,000  pounds  per  square 
inch  of 


t  --  |/ .047  ds* 

This  is  closely  represented  graphically  in  diagram  (e)  of  Fig.  40,  which  may 
also  be  used  for  case  (b)  by  taking  the  depth  of  water  to  the  middle  of  the 
span.  .  For  example,  when  the  depth  of  water  to  the  middle  of  the  span  is 
15  feet,  find  this  in  the  vertical  column  to  the  left,  and  if  6 -inch  sheet  piles 
are  to  be  used,  follow  the  horizontal  through  15  feet  until  it  intersects  the 
6-inch  curve  and  vertically  beneath  will  be  found  the  maximum  spacing  of 
wales,  7  feet  3  inches. 

The  size  and  spacing  of  wales  may  be  taken  from  a  similar  diagram  (f) 
of  Fig.  40,  which  assumes  the  guide  piles  to  be  eight  feet  apart.  The 
spacing  of  struts  or  braces  will  vary  so  much,  that  the  load  must  be  calcu- 
lated, and  when  this  and  the  length  are  known  the  size  may  be  calculated 
from  diagram  (g)  of  Fig.  40,  which  is  for  wet  timber. 

From  the  formula 

p  =  600  —  1(1  —  d), 

in  which/  is  the  allowable  stress  in  pounds  per  square  inch,  /is  the  unsup- 
ported length  in  inches  and  d  the  least  side  of  the  stick  in  inches. 

Where  two  rows  of  sheet  piling  are  to  be  driven  to  form  a  puddle 
chamber,  if  they  are  to  be  efficiently  braced  from  the  inside  of  the  coffer- 
dam, it  will  be  sufficient  to  have  a  thickness  of  puddle  of  from  two  to  four 
feet  to  exclude  the  water,  depending  on  the  quality  of  the  puddle.  Where 
there  is  to  be  no  internal  bracing,  but  two  rows  of  sheet  piling  braced 
together  together  and  filled  with  puddle  are  to  resist  overturning,  the  com- 
mon rule  is  to  make  the  width  of  the  puddle  chamber  equal  to  the  height 
above  ground,  up  to  10  feet.  When  the  height  exceeds  10  feet,  add  one-third 
of  the  excess  height  to  10  feet  for  the  width. 

When  the  puddle  chamber  becomes  very  wide  it  is  often  divided  into 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


57 


several  compartments,  as  was  shown  in  Fig.  5,  and  stepped  in  a  similar 
manner.  When  the  bottom  is  rock  overlaid  with  a  thin  deposit  of  clay  or 
gravel,  the  sheet  piles  may  be  driven  around  an  open  crib- work  for  support, 
as  was  done  at  Harper's  Ferry,  on  the  B.  &  O.  R.  R. 

Where  guide  piles  are  to  be  used,  the  waling  pieces  are  framed  in,  as  was 
specified  on  the  Hutcheson  bridge,  as  shown  at  (a),  Fig.  41,  where  the  guide 
piles  are  of  sawed  timber.  The  wales  are  spaced  slightly  farther  apart  than 
the  thickness  of  the  sheet  piles,  to  allow  clearance  in  driving,  the  space 
between  the  guide  piles  being  filled  out  with  a  key  pile  to  fill  the  panel 
tightly.  This  method  is  but  little  used  with  tight  piling,  that  shown  at  (b), 
Fig.  41,  allowing  the  piling  to  be  driven  continuously,  by  removing  the 


W    IT    TJ 


(</)    ORDINARY    SHEET  PILE    GUIDES. 


, 

m 


w 

m 


(l>)  GUIDKS  WITH  SEPARATORS. 


(c)  SHEET-PILE  CLAMP 


FIG.    41 — SHEET   PILE   GUIDES   AND   CLAMPS. 

spacing  blocks  as  they  are  reached,  and  substituting  bolts  through  the  sheet 
piles,  firmly  connecting  the  piles  and  wales  together, 

A  very  satisfactory  method  is  described  in  the  Engineering  Neiu s  of 
May  12,  1892,  which  was  used  by  A.  F.  Walker.  Having  occasion  to  do  a 
large  amount  of  work  it  was  desirable  not  to  go  to  the  expense  of  squared 
guide  piles.  Round  guide  piles  (P)  were  first  driven  seven  feet  apart,  and 
cut  off  to  a  level.  Caps  were  then  drift-bolted  to  the  tops,  allowing  them 
to  project  slightly  beyond  the  face  of  the  round  piles,  thus  forming  a  perma- 
nent support  for  the  top  of  the  sheet  piles.  Near  the  ground  line  was  placed 
the  clamp,  consisting  of  two  sticks  (X)  and  (Y),  connected  by  three  bolts  and 
drawn  together  as  tight  as  the  intervening  piles  or  pile  and  gauge  block  (G) 
will  permit.  The  stick  (Z)  is  then  forced  forward  by  the  wedges  (W)  until 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


59 


the  space  between  (Z)  and  (Y)  is  the  same  as  the  thickness  of  the  piles. 
The  pieces  (X)  (Y)  (Z)  are  slotted  for  the  middle  bolt,  and  this  permits  of 
some  adjustment.  When  one  of  the  piles  partially  closes  this  slot,  a  notch 
is  cut  in  the  same  large  enough  to  receive  the  bolt,  and  the  bolt  is  then 
slipped  up  to  it  and  tightened.  This  allows  of  the  next  pile  being  driven  as 
close  as  the  others.  When  one  panel  has  been  completed  the  nuts  are 
removed  and  the  clamps  moved  forward  to  the  next  one,  a  notch  being  cut 
in  the  end  pile  to  receive  the  end  bolt  of  the  clamp.  The  piles  are  sharp- 
ened flatwise  with  a  little  more  slope  on  the  side  facing  the  guide  piles, 
giving  them  a  tendency  to  drive  away  from  the  guide  pile  at  the  foot  and 
bear  against  the  cap  at  the  top.  A  slight  bevel  is  also  given  to  the  edge  to 
make  the  foot  crowd  the  adjoining  pile.  During  the  first  half  of  the  driving, 
the  joint  is  held  a  little  open  at  the  top,  but  during  the  latter  half,  pressure 


FIG.    43 — SEWER   COFFER-DAM.        BOSTON    SEWERAGE    SYSTEM. 

is  brought  to  crowd  it  toward  its  neighbor,  and  the  joint  will  close  as  tightly 
as  possible. 

The  use  of  single  pieces  of  timber  as  wales,  against  which  the  sheet  piling 
is  driven,  is  illustrated  in  the  use  of  method  (b)  of  Fig.  38,  by  Benj.  Doug- 
las, Bridge  Engineer  of  the  Michigan  Central  Railway.  The  coffer-dam 
(Fig.  42)  was  built  without  guide  piles,  the  wales  being  12x1 2-inch  timber 
bolted  against  the  outside  of  the  sheet  piling,  by  the  brace  rods  one  inch  in 
diameter.  The  wales  are  held  in  place  vertically  by  bracing  of  2x1 2-inch 
pine  plank,  which  are  spiked  on  as  verticals  and  diagonals  to  form  a  truss 
and  also  to  stiffen  the  framework  in  general. 

The  sheet  piling  is  5x12,  and  after  being  driven  into  the  hard  gravel 
bottom,  the  cracks  were  lapped  by  I -inch  boards  The  bottom  was  uneven 


60  THE  COFFER-DAM  PROCESS  FOR  PIERS. 

and  accounts  for  the  difference  in  height,  the  excavation  at  the  high  end 
being  dumped  outside  at  the  low  end,  to  assist  in  making  the  dam  tight. 
The  puddle  chamber  was  2  feet  8  inches  wide  and  was  filled  with  clayey 
gravel.  The  plan  also  shows  the  grillage  in  place  for  receiving  the  founda- 
tion courses  of  the  stonework.  This  is  formed  by  12x12  timber  crossed,  and 
drift-bolted  together  with  1-inch  round  and  18-inch  long  drift  bolts. 

The  account  of  the  Arthur  Kill  bridge  foundation  in  Vol.  27  of  the 
''Transactions  of  the  American  Society  of  Civil  Engineers,"  by  A.  P. 
Boiler,  Consulting  Engineer,  covers  a  very  interesting  experience  with  sheet 
piling  on  Pier  No.  5:  "This  pier  is  near  the  edge  of  the  marsh  forming  the 
Staten  Island  shore,  which  is  barely  flooded  at  extreme  high  tides.  Borings 
indicated  about  thirty  feet  from  the  surface  to  hard  bottom,  consisting  of 
mud,  mud  and  clay,  clay  and  shale  to  the  bottom  of  shaley  clay,  in  which 
the  pier  was  to  be  founded.  Experience  on  other  work  of  a  similar  char- 
acter, indicated  that  the  founding  of  this  pier  would  be  accomplished  with 
little  difficulty.  The  area  of  the  foundations  was  inclosed  with  a  tongued 
and  grooved  sheet  pile  dam  of  4-inch  yellow  pine  plank.  But  it  was  found 
impossible  to  hold  the  plank  at  a  depth  of  fifteen  feet,  the  mud  and  clay 
becoming  puddled  with  water,  and  despite  all  efforts  at  bracing,  the  plank 
shoved  inward  to  such  an  extent,  as  to  spoil  the  whole  dam  before  we  were 
half  way  down.  A  second  dam  was  therefore  driven  around  the  first  one, 
but  this  time  with  10xl2-inch  tongued  and  grooved  timbers,  in  one  length 
to  reach  the  extreme  bottom.  These  timbers  were  grooved  by  slitting  the 
grooves  out  at  the  mill  with  a  circular  saw  and  chiseling  the  blank  so  formed 
free.  The  tongue  was  an  independent  spline,  2^x4  inches,  of  dry  wood 
and  nailed  in  one  groove.  The  timbers  were  shaped  at  the  feet  to  drive 
close.  This  dam  was  hard  driving,  but  was  finally  accomplished,  when 
digging  was  resumed  and  the  old  dam  removed  piecemeal  as  we  could  get  in 
the  braces.  The  bottom  was  reached  within  a  perfect  dam,  with  only  one 
bad  leak  in  the  northwest  corner,  due  to  the  shattering  of  a  small  piece  of  one 
tongue  during  the  driving.  As  it  was  impossible  to  stop  this  leak  from  the 
inside,  and  the  outside  was  inaccessible,  to  prevent  washing  the  concrete, 
the  leak  was  led  off  in  a  box  at  the  side  of  the  dam  to  the  sump  well,  and 
the  footing  course  of  concrete,  filling  the  whole  area  of  the  dam  about  seven 
feet  deep,  was  gotten  in  place." 

This  example  emphasizes  in  a  very  decided  manner  many  of  the  state- 
ments that  have  been  made  heretofore.  While  no  doubt  the  removal  of  the 
old  dam  was  attended  with  much  expense,  its  inclosure  entirely  within  the 
new  sheet  piling  rendered  the  prosecution  of  the  work  comparatively  certain. 

An  example  of  the  driving  of  sheet  piling  on  a  slant,  to  prevent  crowd- 
ing in  at  the  bottom  is  shown  in  Fig.  43,  which  is  a  cross-section  of  a  sewer 
coffer-dam  used  on  the  Metropolitan  Sewerage  Systems  of  Massachusetts  by 


THE  COFFER-DAM  PROCESS   FOR  PIERS. 


61 


Howard  A.  Carson,  chief  engineer,  and  described  in  the  Engineering  News 
of  Feb.  8,  1894. 

The  outlet  into  the  ocean  at 
Deer  Island  begins  at  a  point 
about  sixty  feet  inside  the  high 
water  line  and  about  1,850  lineal 
feet  is  from  five  to  ten  feet  below 
high  water.  This  necessitated 
the  coffer-dam,  which  was  con- 
structed with  bents  every  six 
feet  and  with  2-inch  plank  inside 
the  high  water  line,  but  for  the 
remaining  distance  of  4-inch 
matched  plank.  The  excavation 
was  done  by  means  of  buckets, 
traveling  derricks  and  dump  cars, 
the  latter  being  emptied  at  the 
sides  and  ends  of  the  trench. 
The  leakage  from  the  ocean  was 
kept  out  by  using  centrifugal 
pumps,  which  pumped  a  maxi- 
mum of  46,000  gallons  per  hour. 
The  concrete,  which  has  large 
boulders  imbedded  in  its  surface 
the  size  of  paving  stones,  was  car- 
ried up  to  the  level  of  the  ocean 
bottom. 

From  the  middle  of  June, 
1893,  when  the  work  was  begun, 
to  the  end  of  September,  526  feet 
of  trench  was  completed.  The 
size  of  the  trench  was  14  feet 
average  depth  and  10.  8  feet  aver- 
age  width,  which  made  the  ex- 
cavation average  5.6  yards  per 
lineal  foot.  The  cost  for  the 
trench,  including  coffer-dam, 
sheeting  left  in  and  back  filling 
was  $44.00  per  lineal  loot. 

Casual  mention  has  been  made  in  several  places  of  the  use  of  Wakefield 
sheet  piling  which  was  illustrated  at  h  and  h'  of  Fig.  38  and  which  is  further 
shown  in  Fig.  44.  View  No.  1  is  of  a  corner  which  is  formed  as  in  the  plan 


44_WAKEFIELD  SHEET  PIWNG. 


62 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


No.  2,  a  tongue  being  bolted  on  the  side  of  a  pile,  when  the  corner  is  reached 
as  in  No.  3.  Any  angle  is  turned  by  a  similar  method,  which  is  shown  by 
No.  4,  or  the  piles  may  be  driven  to  form  a  curve.  The  essential  features 
of  the  system  ?re  the  triple  lap  or  long  tongue  and  groove  which  excludes 
the  water,  and  the  use  of  ordinary  plank,  which  can  be  easily  obtained. 
The  center  planks  should  be  sized  to  a  uniform  thickness,  to  insure  the 
tongues  fitting  the  grooves,  and  to  make  driving  easy,  while  the  three  plank 
are  to  be  bolted  and  spiked  together  to  cause  them  to  act  as  a  compound 
beam  and  not  as  separate  plank  like  the  system  of  (b)  Fig.  38.  It  is 
recommended  to  use  a  2^ -inch  tongue  on  1-inch  boards  and  ^-inch  bolts. 
For  1^-inch  plank  a  3-inch  tongue,  for  2-inch  and  2^-inch  plank  a  3%- 
inch  tongue  and  ^-inch  bolts,  while  for  3-inch  plank  a  3^-inch  tongue  and 
^i-inch  bolts  are  to  be  used,  and  the  same  size  bolts  for  4-inch  plank,  but  a 
4-inch  tongue.  Two  bolts  are  to  be  staggered  in  every  five  to  eight  feet  of 
the  length  of  the  pile  and  spikes  used  between  the  bolts  on  long  piles. 


FIG.    45 — TYPE    OF    MOMENCK    AND    HARPER'S    FERRY    COFFER-DAMS. 

The  La  Grange  lock  on  the  Illinois  river  was  inclosed  with  this  piling, 
under  the  direction  of  Major  W.  L.  Marshall,  Corps  of  Engineers.  It  was 
intended  to  back  the  sheeting  with  earth,  but  as  both  dredges  broke  down 
the  water  tightness  was  entirely  dependent  on  the  Wakefield  piling,  and 
under  a  7-feet  head  no  leaks  were  developed.  The  piles  were  made  of  three 
plank  3x12  inches  by  22  feet  long  and  with  a  3-inch  tongue;  they  were 
driven  by  three  pile  drivers  with  hammers  of  from  2,800  to  3,000  pounds 
through  sand  and  mud,  and  in  one  place  a  layer  of  shells.  There  was  no 
difficulty  experienced  in  driving  the  piles  without  special  appliances. 

The.  use  of  1-inch  boards  in  this  form  (Fig.  45)  is  described  by  H.  F 
Baldwin,  chief  engineer  of  the  C.  &  E.  I.  Railway:  "In  constructing  our 
second  track  over  the  Kankakee  river  at  Momence,  111.,  it  was  necessary  to 
extend  the  piers  in  that  river.  The  bottom  is  limestone  and  the  surface  is 
very  irregular.  We  tried  several  days  and  finally  succeeded  in  constructing 
a  coffer-dam  with  two  parallel  walls  of  sheet  piling.  We  then  tried  the 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  63 

Wakefield  triple  lap  piling,  constructed  of  1-inc'i  boards  sharpened  to  an 
edge,  2 ^-tongue  and  groove,  which  were  driven  with  sledges  until  the  piles, 
which  were  soft  pine,  conformed  to  the  uneven  surface  of  the  rock.  This 
piling  was  driven  around  cribs  loaded  with  stone,  and  after  the  piling  was 
driven,  gravel  was  put  outside  the  coffer-dam,  after  which  no  trouble  was 
experienced  in  pumping  out  the  water." 

The  work  on  the  foundations  of  the  new  B.  &  O.  R.  R.  bridge,  over  the 
Potomac  river  at  Harper's  Ferry  was  similar  in  many  respects  to  the  above, 
and  the  system  was  found  to  be  very  satisfactory. 

Reference  was  made  to  the  use  of  this  piling  on  the  Charlestown  bridge 


FIG.    46 — COFFER-DAM    ON    CHARLESTOWX    BRIDGE. 

at  Boston  and  the  driving  of  the  piles  shown  in  Fig.  39.  The  work  was 
under  the  charge  of  Jno.  E.  Cheney,  Consulting  Engineer,  and  was  success- 
fully carried  out.  The  piling  were  driven  principally  as  forms  for  concrete 
foundations  and  but  little  care  was  taken  to  make  the  dams  watertight. 
After  the  concrete  was  deposited  they  were  used  as  coffer-dams  against  a  6 
or7-feet  head  of  water.  They  were  18  feet  6  inches  by  119  feet  (Fig.  46) 
and  in  some  cases  were  thirty  feet  below  low  water  or  forty  feet  below  mean 
high  water.  The  piling  was  made  of  2-inch  plank  and  driven  with  an  ordi- 
nary pile  driver.  The  pumping  was  done  with  a  20-inch  centrifugal  pump 


OF  TH* 

UNIVERSITY 


64  THE   COFFER-DAM  PROCESS  FOR  PIERS. 

and  in  some  cases  a  12-inch  Follansbee  pump  of  the  propeller  type  was  used. 
The  construction  of  the  sewerage  system  at  Fort  Monroe,  Va.,  under 
Capt.  Thos.  L.  Casey,  Corps  of  Engineers,  is  described  in  the  report  of  the 
Chief  of  Engineers  of  1896.      The  work  was  done  on  the  general  plans  of 
Rudolph  Hering,  Consulting  Sanitary  Engineer.     One  of  the  special  diffi- 
culties encountered  "was  the  building  of  a  sewage  tank  fifty  feet  in  diameter, 
with  walls  of  brick   two  feet  in  thickness,  exteriorly  diminishing  to  three 
feet  at  the  center,  the  inferior  reference  of  which  was  twenty  feet  below  low 
water.     As  described  in  the  report  referred  to,  this  was  accomplished  very 
successfully  by  excavating  a  large  area  to  the  reference  of  ground  water,  some 
five  or  six  feet  below  the   surface,  and  then  driving  by  the  pile  driver  and 
water  jet  combined,  two  concentric  twelve-sided  polygons  of  Wakefield  sheet 
piling  28  feet  in  length,  30  and  22  feet  from  the  center,  about  the  circumfer- 
ence of  the  shallow  excavation.     (Fig.  47.)     The  material,  consisting  of  fine 
water-soaked  sand,  with  a  small  admixture  of  clayey  matter  and  fine  gravel, 
was  then  excavated  between  the  polygons  to  a  reference  of  20  feet,  trans- 
verse shoring  braces   bearing  upon  stout  stringers  being  put  in  at  intervals 
as  the  work  proceeded.     The  material  did  not  vary  much  in  its  general 
nature,  but  a  number  of  old  piles  were  taken  up,  some  of  which  did  consid- 
erable injury  to  the  sheet  piling  when  driven,  as  shown  in  the  subsequent 
excavation.     The  water  was  controlled  by  a  powerful  steam  pump  having 
its  point  of  suction  fixed,  the  water  being  permitted  to  flow  toward  it  through- 
out the  circumference.     It  was  noticed  that  ground  water  came  through  the 
sheeting  very   freely  at  first,  but  that  it  constantly  ceased  to  flow  to  any 
great  extent  at  a  height  of  a  few  feet  above  the  point  of  excavation  as  this 
continually   descended,  owing  to  the  rapid  drainage  of  the  strata.      The 
interior  core,  in  fact,  t  ecame  quite  dry,  so  that  in  excavating  after  the  walls 
were  laid,  no  water  was  encountered  until  the  bottom  of  the  external  concrete 
ring  had  been  virtually  laid  bare.     Upon  attaining  the  reference — 20  feet, 
the  excavation  ceased  and  hand-mixed  concrete  was  deposited  directly  upon 
the  bottom .  as  this  was  considered   to  be  sufficiently  firm,  the  pump  being 
stopped  temporarily  in  order  to  prevent  a  flow.     The  concrete  was  rammed 
firmly  against  the  outer  sheeting  externally  and  against  plank  forms  with 
triangular  cross-section  resting  against  the  inner  sheeting  internally,  until 
six  feet  in  depth  had  been   put  in   place.     The  portion  of  the  ring  at  the 
pump  suction  was  filled  rapidly  with  concrete  in  bags.      The  2-feet  brick 
wall  was  then  carried  up  from  the  axia)  line  of  the  concrete  ring,  the  space 
between  the  wall  and  the  outer  sheeting  filled  with  sand,  except  about  six 
inches  at  the  base  of  the  wall,  which  was  of  concrete.     The  braces  were 
removed  as  successively  attained,  the  inner  prism  of  dry  sand  being  held 
securely  by  the  sheeting  and  the  extreme  top  struts,  which  were  left  in  place 
until  the  inner  core  was  completely  excavated.      On  the  completion  of  the 
latter  work  to  reference — 20  feet,  the  water  which  came  in  freely  from  with- 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  6$ 

out  under  the  concrete  ring  at  several  points  was  conducted  in  a  peripheral 
trench  to  the  fixed  point  of  pumping.  No  water  came  upward  and  the 
middle  portions  of  the  bottom  became  perfectly  dry.  The  inner  .sheeting 
was  cut  off  at  the  base  of  the  ring,  boards  were  placed  transversely  over  the 
peripheral  trench,  a  duck  tarpaulin  coated  with  hot  asphalt  laid  down, 
and  concrete  rammed  in  place  until  the  concave  bottom  with  sump 
channel  had  been  completed,  leaving  only  the  pipe,  through  which 
the  ground  water  had  been  pumped  continually,  night  and  day  at  about  1,000 
gallons  per  minute,  penetrating  the  concrete.  In  order  to  fill  this  pipe,  it 
was  cut  off  above  the  level  of  permanent  ground  water,  and  after  the  water 


FIG.  47. — RESERVOIR    COFFER-DAM.       FORT    MONROE,    VA. 

within  had  attained  the  level  of  ground  water  in  the  surrounding  area  and 
had  become  perfectly  quiescent,  neat  cement  in  paper  bags  was  dropped 
within,  being  retained  at  the  bottom  by  the  closed  valve;  the  bags  were 
readily  broken  up  by  a  long  pole  thrust  down  the  pipe.  The  latter  was  then 
cut  off  at  the  level  of  the  bottom  and  a  coating  of  cement  plaster  applied 
throughout.  The  resultant  leakage  through  the  bottom  did  not  exceed  about 
a  gallon  a  minute  and  this  will  be  greatly  reduced  by  the  infiltration  of  sand 
from  beneath." 

Further  illustrations  of  the  use  of  sheet  pile  coffer-dams  will  be  given; 
then  the  operations  of  dredging,  pumping  and  concreting  described  at  some 
length. 


ARTICLE   VI. 

THE    COFFER-DAM    PROCESS    FOR    PIERS. 

CONSTRUCTION   WITH   SHEET   PILES. 

VARIOUS  combinations  of  the  sheet  piling  shown  in  Fig.  38  may  be 
made,  when  occasion  demands,  or  modifications  may  be  made 
that  will  perhaps  render  the  available  material  more  effective. 
For  example,  the  form  (g)  may  be  modified  to  the  form  shown  in  Fig.  48, 
which  has  the  advantage  of  a  wider  lap,  and  should  the  piles  not  draw 
tight  together  in  driving,  no  crack  will  be  left  open  to  admit  the  water. 
Then  the  piles  of  this  form  will  act  as  guides  to  the  ones  being  driven, 
similar  to  the  ordinary  tongue  and  groove  piling.  Other  combinations  and 
arrangements  will  readily  suggest  themselves  as  necessity  may  demand. 

The  use  of  sheet  piling  is  often  accompanied  by  a  great  deal  of  trouble 
in  producing  tightness,  and  as  a  matter  of  precaution,  the  very  best  method 
possible  should  be  adopted  in  making  the  piling. 

The  coffer-dams  constructed  at  Chattanooga  for  the  Walnut  street  bridge 
over  the  Tennessee  River,  under  Edwin  Thacher,  Consulting  Engineer,  were 
described  in  the  Engineering  Arews  of  May  16,  1891. 

Four  piers  were  founded  by  this  method,  but  the  account  of  pier  number 
two  will  fully  illustrate  the  work.  The  bed  rock  which  was  level,  was 
covered  by  cemented  sand,  gravel  and  boulders,  of  which  320  yards  were 
removed.  The  coffer-dam  was  built  eighteen  feet  high,  or  eight  feet  above 
low  water,  to  provide  for  a  future  rise.  The  inside  was  made  large  enough 
to  allow  of  a  space  of  four  feet  all  around  the  base  of  the  pier,  and  the 
space  between  the  sheet  piles  for  a  puddle  chamber  was  made  nine  feet. 
This  was  filled  to  an  average  of  twelve  feet  with  a  clay  puddle,  of  which 
there  was  900  yards  used.  As  a  protection,  there  was  placed  outside  the 
dam  about  450  yards  of  puddle,  and  a  breakwater  was  built  up  stream. 
About  38,000  feet  of  timber  was  used  in  the  dam  and  breakwater. 

After  the  dam  was  completed  a  rise  of  thirty  feet  washed  out  about  half 
the  puddle,  and  one  end  was  crushed  by  a  raft,  but  the  repairs  were  made 
v\'ithout  serious  trouble.  No  extra  amount  of  pumping  was  required  on  any 
of  this  work  except  pier  number  three,  where  the  seams  in  the  bed  rock  re- 
quired pumps  with  a  capacity  of  5,000  gallons  per  minute,  and  these  did 
not  suffice  to  keep  the  water  down,  until  the  seams  were  closed  by  laying 
sacks  of  concrete  over  them  and  weighting  them  down  with  large  stones. 
The  location  of  these  seams  is  shown  in  Fig.  49. 

The  framework  and  wales  for  a  sheet  pile  coffer-dam,  used  in  founding 

66 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  67 

the  pier  for  the  Baltimore  street  bridge  at  Cumberland,  Md.,  are  shown  in 
Fig.  50,  and  this  was  described  in  the  Engineering  News  of  July  21,  1892, 
by  H.  P.  Le  Fevre,  engineer  in  charge.  The  frame  was  built  in  place  on 
two  canal-boats  and  after  completion  was  suspended  from  the  old  Bollman 
truss  which  the  new  bridge  replaced. 

The  depth  of  the  water  was  four  feet,  and  about  six  feet  of  very  loose 
quicksand  and  small  round  pebbles  overlaid  the  hard  bottom. 

After  the  boats  were  removed,  the  frame  was  lowered  to  its  place,  the 
sheet  piling  driven  and  the  dam  pumped  out  with  a  six-inch  pump.  The 
foundation  was  laid  on  the  hard  bottom  under  the  quicksand,  after  this  had 
been  removed. 

The  grillage  was  made  of  two  courses  of  15x1 5-inch  clear  white  oak, 
around  which  was  built  a  framework,  and  the  open  spaces  of  the  grillage 
were  then  filled  with  a  concrete,  made  up  of  one  part  of  Cedar  Cliff  cement 
to  two  parts  of  sand  and  four  parts  of  hydraulic  limestone,  broken  to  pass 


V    \ 

II      I,     \ 

!!      i        \ 


•• 
n       ' 

n          I 


FIG.   48 — COMPOUND  SHEET  PILE. 

through  a  two-inch  ring.  Upon  this  was  laid  the  footing  courses  of  the 
masonry. 

Another  ordinary  sheet  pile  coffer-dam  which  gave  good  satisfaction, 
was  used  at  the  Sandy  Lake  dam  on  the  Mississippi  River,  by  Major  W.  A. 
Jones,  corps  of  engineers,  and  as  the  account  contains  so  much  of  value,  it 
will  be  quoted  in  full  from  the  1894  report  of  the  Chief  of  Engineers. 

"The  coffer-dam  is  composed  of  two  rows  of  round  piles,  twelve  feet 
from  center  to  center  of  piles,  with  the  exception  of  sixty-two  feet  of  the 
east  end  of  the  upper  part,  where  they  were  driven  fourteen  feet  from  center. 
The  piles  in  each  row  are  eight  and  one-half  feet  from  center  to  center,  cut 
off  at  an  elevation  of  1217  feet  above  sea  level  and  capped  with  12x12  inch 
timber.  The  inside  row  of  sheeting  is  4x12  inch,  and  the  outside  6x12  inch 
plank.  The  sheeting  is  cut  off  at  an  elevation  of  1218  feet  above  sea  level, 
or  two  feet  below  the  flowage  line.  One-inch  rods  of  round  iron,  eight  and 
one-half  feet  apart,  pass  through  the  caps  to  prevent  the  filling  from 
spreading  the  two  lines  of  sheeting  at  the  top. 

In  May,  1892,  when  a  flood  occurred,  the  outside  of  the  cofferdam  was 
raised  three  feet  by  splicing  three-inch  planks  to  the  outside  row  of  sheet- 


68 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


ing  and  then  filling  the  triangular  prism  thus  formed  with  earth.  The  cross 
section  of  Fig.  51  gives  an  idea  of  the  dam  above  the  bottom,  while  the 
longitudinal  section  shows  the  framing  down  to  where  it  rests  on  the  bot- 
tom, the  frames  being  joined  by  the  one-inch  lateral  rods  of  iron. 

The  total  length  of  the  coffer-dam  is  829  feet,  of  which  742  feet  is  like 
that  shown  in  cross  section  and  the  other  87  feet  like  that  shown  in  the 
longitudinal  section. 

The  number  of  round  piles  driven  in  the  foundation  is  1.605.  The  driv- 
ing was  commenced  on  November  12,1891,  and  completed  on  August  2 1 , 1 893 . 

The  material  in  the  foundation  is  sand,  excepting  in  the  lower  right 
hand  corner,  where  there  is  some  blue  clay  overlying  the  sand.  The  sand 
in  the  foundation  is  not  as  compact  as  it  is  usually  found  in  the  bed  of 
streams.  In  the  south  half  of  the  dam,  the  surface  settled  from  four  to  six 


EI.O 


EI.-S 


1 

I 

1 

\  Bed  of  River. 


ivest. 


fast 


FIG.    49 — CHATTANOOGA    BRIDGE    BED    ROCK   PIER   NO.   3. 

inches  during  the  driving.  As  the  surface  was  settling,  the  driving  became 
harder  all  the  time.  In  the  north  half,  which  embraces  the  navigable  pass, 
there  was  some  settlement,  but  it  was  not  as  noticeable  as  in  the  south  half. 
The  surface  had  probably  settled  by  the  jarring  of  the  hammers  while  the 
first  half  was  being  driven.  The  penetration  of  the  piles  is  also  greater 
than  it  usually  is  in  sand  foundations  in  the  bed  of  streams. 

The  piles  were  all  of  Norway  pine  and  well  seasoned.  Two  Mundy 
steam  hoisting  engines  were  used  in  driving,  one  a  single  cylinder  and  the 
other  a  double  cylinder  engine.  In  operating  the  hammer  an  inch  and  a 
half  manila  rope  was  attached  to  the  pin  connecting  the  lugs  of  the  ham- 
mer, then  passed  over  the  sheave  at  the  top  of  the  leaders,  and  next  around 
the  drum  of  the  hoisting  engine. 

When  the  hammer  falls,  it  pulls  the  rope  with  it  and  unwinds  it  from  the 
drum.     This  is  what  is  termed  driving  with  a  "slack  line."     The  blows  are 


;o 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


more  rapid  and  keeps  the  material  around  the  piles  looser  than  it  would  be 
in  the  case  of  using  nippers.  Iron  rings  of  5/gx2^  inches  Norway  iron 
were  used  to  protect  the  head  of  the  pile. 

It  is  a  well-known  fact  in  pile  driving  that  it  is  very  important  to  keep 
the  material  from  settling  around  the  pile,  once  it  has  been  loosened,  until 
the  pile  is  down;  for  when  the  material  has  settled,  or  even  partially,  the 
penetration  is  diminished.  The  greatest  load  on  a  bearing  pile  is  about  13^ 
tons. 

Sheet  piling  was  driven  by  a  pile  driver,  assisted  by  a  jet  of  water  from  a 
steam  force  pump.  In  driving  all  sheet  piles  a  cast-iron  cap  or  follower  was 
used  which  fitted  over  the  head  of  the  pile.  On  the  upper  side  of  the  fol- 
lower there  is  a  wooden  block  of  some  seasoned  or  close  grained  wood  which 
receives  the  blow  of  the  hammer.  This  device  saves  the  head  of  the  pile 
from  being  battered  or  splintered,  and  the  pile  can  be  driven  to  a  greater 
depth  than  it  could  be  without  it. 


'21' 


m 


FIG.   51 — SANDY  I.AKE   COFFER-DAM. 

In  first  using  the  jet  on  a  sheet  pile,  a  groove  was  made  in  the  inner 
edge  to  receive  a  half-inch  gas  pipe,  which  was  connected  to  the  force  pump 
by  means  of  an  inch  and  a  half  hose.  The  aperture  at  the  lower  end  of 
the  gas  pipe  was  reduced  to  a  diameter  of  about  three-eighths  inch.  The 
water  was  thus  forced  to  the  bottom  of  the  pile,  and  the  sand  loosened. 

This  worked  well  until  the  sheet  pile  struck  gravel,  when  the  nozzle  of 
the  pipe  would  become  battered  or  filled  with  gravel.  The  pressure  in  the 
hose  would  then  burst  a  coupling  somewhere.  Another  source  of  trouble 
was  the  frequent  breakages  in  the  connection  between  the  pipe  and  the 
hose,  on  account  of  the  jarring  of  the  hammer.  This  plan  after  awhile  was 
abandoned  and  the  nozzle  of  the  pipe  was  thrust  by  hand  under  the  point  of 
the  pile.  The  piles  are  driven  in  the  ground  from  12  to  14  feet. 

The  construction  of  the  Main  street  bridge  at  Little  Rock,  Arkansas,  in- 
volved the  construction  of  two  coffer-dams,  for  piers  No..  5  and  No.  6.  This 
work  was  done  under  the  direction  of  Edwin  Thacher,  Consulting  Engineer, 
whose  original  specifications  called  for  pile  foundations  for  these  piers,  the 
piles  to  be  driven  to  bed  rock  and  cut  off  four  feet  below  low  water,  to  re- 
ceive a  grillage  of  12x1 2-inch  timbers  to  receive  the  masonry.  The  size  of 


THE    COFFER-DAM  PROCESS  FOR   PIERS. 


FIG.    52 — COFFER-DAM     AND    CONCRETE    PIER,    LITTLE    ROCK,    ARK. 

the  grillage  being  12  and  13  feet  wide  by  34  feet  long  and  resting  on  forty- 
eight  and  sixty  piles  respectively,  the  piles  being  of  good  sound  oak  or  pine 
at  least  eight  inches  in  size  at  the  small  end  and  not  less  than  twelve  inches 
at  the  butt  when  sawed  off. 

The  coffer-dams  were  constructed,  as  can  be  seen  from  the  view  in  Fig. 
52,  by  driving  guide  piles,  to  the  top  of  which  are  drift  bolted  square  guide 
timbers.  The  sheet  piling  of  three-inch  tongue  and  groove  stuff  was  driven 
against  the  outside  of  this  timber,  and  the  excavation  banked  up  against 


72  THE   COFFER-DAM  PROCESS  FOR  PIERS. 

the  outside.     They  gave  excellent  satisfaction  and  caused   little  trouble  as 
the  water  was  shallow. 

The  piers  were  constructed  of  Portland  cement  concrete,  the  facing  of 
two  inches  thickness  being  a  mortar  of  one  part  of  cement  to  two  parts  of 
sand  while  the  balance  was  of  concrete  of  one  part  cement,  three  parts  sand 
and  six  parts  of  broken  stone. 

Where  sheet  piles  are  to  be  driven  on  rock  bottom  or  through  earth  or 
gravel  to  rock  bottom,  they  should  be  driven  hard  enough  to  broom  up  and 
form  a  close  joint  with  the  rock.  This  has  been  accomplished  also  by  driv- 
ing the  piles  with  a  thin  edge  until  they  fit  the  rock  bottom,  when  they  are 
drawn  and  after  cutting  them  to  conform  to  the  contour  of  the  rock,  they  are 
redriven,  thus  forming  a  tight  joint.  This  method  while  very  good,  is  too 
expensive  for  general  adoption. 

Coffer-dams  are  quite  frequently  constructed  for  the  repair  or  removal  of 
existing  piers.  A  pier  which  was  constructed  in  1840  in  the  river  Parnitz, 
at  Stettin,  Germany,  became  an  obstruction  to  navigation  and  it  was  de- 
cided to  remove  it. .  The  work  was  described  in  the  Engineering  News  of 
July  14,  1892. 

Its  exterior  showed  a  facing  of  granite  laid  in  hard  Roman  cement,  and 
soundings  revealed  the  existence  of  a  course  of  sheet  piling  around  the  pier, 
with  a  protection  of  rip-rap  at  its  foot.  The  original  drawing  of  the  pier 
showed  a  pile  foundation.  The  specification  prescribed  the  use  of  the  old 
course  of  sheet  piling,  shown  at  A  on  accompanying  cuts,  for  the  construc- 
tion of  the  coffer-dam.  Owing  to  the  belief  that  the  existing  sheet  piling, 
after  having  served  such  a  length  of  time,  would  not  be  sound  enough  to 
permit  of  its  use  in  the  erection  of  a  coffer-dam,  local  contractors  could  not 
be  found  and  the  work  was  let  to  an  outside  contractor. 

The  preliminary  work  was  begun  by  picking  up  the  rip-rap  around  the 
foot  of  the  pier  with  a  claw  dredger  mounted  on  a  raft.  Some  of  the  stones 
weighed  as  much  as  a  ton.  The  bottom  of  the  river,  after  the  rip- rap  had 
been  cleared  away,  was  found  to  be  covered  with  a  layer  of  concrete,  consist- 
ing of  pieces  of  brick  and  cement.  This  was  brought  up  in  large  slabs.  The 
pier  itself  was  found  to  be  of  rubble  masonry,  composed  of  irregular  shaped 
granite  blocks  with  the  interstices  filled  with  brick,  laid  in  cement  mortar. 
The  single  stones  were  detached  and  swung  off  by  the  claws  of  the  dredger. 
Their  average  weight  was  about  one  and  a  half  tons. 

After  the  masonry  had  been  pulled  down  to  nearly  the  level  of  the  water 
a  row  of  sheet  piling,  shown  at  b  in  Fig.  53,  consisting  of  piles  seven  inches 
thick,  was  driven  to  a  depth  of  nearly  ten  feet.  The  space  between  the  old 
and  new  sheet  piling  was  filled  with  blue  clay.  To  keep  the  interior  free 
from  water  two  pumps  were  employed.  After  putting  in  the  necessary 
bracing  the  work  of  removing  the  masonry  to  the  bed  of  the  river  was  con- 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  73 

tinued.  A  shell  of  the  latter,  however,  was  left  standing.  Then  the  timber 
platform  on  which  the  masonry  had  been  resting  and  the  layer  of  concrete 
below  were  taken  out,  exposing  a  layer  of  clay  underneath.  While  attempt- 
ing to  pull  one  of  the  foundation  piles  a  stream  of  water  rushed  through  the 
opening  thus  formed,  so  that  this  plan  had  to  be  given  up  and  blasting  re- 


cJecr/orT,  ReaUy  for  D'asting. 


Sectfot\fOriOir\Ql  Pier. 


Z6'  9" — 


Plor\,  R?<3dy  for  Blasting^. 


FIG.   53 — REMOVAL    OF   MASONRY    PIER    AT   STETTIN,    GERMANY. 

sorted  to.  To  do  this  the  tops  of  the  piles  were  bored  to  a  depth  of  thirteen 
feet  and  filled  with  8.8  pounds  of  dynamite  each.  The  initial  charges  con- 
sisted of  10.6  ounces  in  air-tight  canisters.  The  shell  of  masonry  left  stand- 
ing received  four  cubical  charges  of  8.8  pounds  each.  In  all  sixty-eight 
charges,  consisting  of  616  pounds  of  dynamite,  were  used.  The  electric 
current  for  the  blast  was  divided  into  three  currents,  each  being  attached  to 


74  THE  COFFER-DAM  PROCESS  FOR  PIERS. 

an  induction  apparatus.  The  blasting,  however,  did  not  prove  to  be  as 
effective  as  was  anticipated,  owing  to  the  dissolving  action  of  the  water,  and 
several  charges  were  taken  out  intact.  The  clearing  away  of  the  wreck  was 
almost  entirely  done  by  the  claw  dredges.  The  piles,  which  were  split  and 
loosened  in  their  sockets  by  the  force  of  the  explosion,  were  pulled  up  by 
windlasses  mounted  on  flat  boats.  The  work  of  removing  the  pier  lasted 
nearly  nine  months  and  the  cost  was  about  $8,700. 

Another  example  of  the  removal  of  a  pier  was  at  Gadsden,  Alabama, 
where  a  pivot  pier  in  the  Coosa  river  had  tilted.  The  pier  had  been  built 
originally  in  a  water-tight  caisson  and  was  supposed  to  have  been  founded 
on  solid  rock,  but  by  some  error  a  layer  of  gravel  was  left  underneath  and 
eventually  the  pier  tilted  down  stream  seven  feet,  nearly  throwing  the  swing 
span  into  the  river. 

After  the  span  had  been  blocked  up  to  allow  the  passage  of  trains,  a  coffer- 
dam was  built  around  the  pier  to  give  plenty  of  clearance  to  the  old  caisson. 
(Fig.  54.)  This  was  constructed  by  driving  three  rows  of  sheet  piling 
through  sand  and  gravel  to  bed  rock  and  puddling  between  them. 

The  sand  and  gravel  over  the  rock  was  not  removed  from  the  bottom  of 
the  puddle  chamber  before  puddling  and  a  great  deal  of  trouble  was  expe- 
rienced all  through  the  work  by  leakage  through  the  porous  gravel.  It  is 
probable,  too,  that  a  poor  joint  was  made  between  the  sheet  piling  and  the 
rock. 

Bents  were  erected  upon  the  sides  of  the  coffer-dam  and  by  driving  piles 
into  the  puddle  and  inside  the  dam,  to  carry  a  truss  on  each  side  of  the 
span,  which  carried  the  drum  and  supported  the  main  trusses  at  the  center. 
When  this  had  been  tested  by  loading  with  trains  of  ore  upon  the  bridge 
and  found  to  be  satisfactory,  work  was  at  once  begun  upon  the  removal  of 
the  old  pier,  by  means  of  two  fixed  derricks  on  the  false  work  and  one  float- 
ing derrick.  The  stones  were  marked  as  they  were  removed  to  insure  their 
return  to  proper  places  when  the  pier  was  rebuilt,  and  were  taken  to  the 
shore  until  needed  again.  When  the  masonry  was  all  removed  the  grillage 
was  broken  up  and  taken  out,  after  which  the  gravel  inside  the  coffer-dam 
was  cleaned  out  down  to  bed  rock.  New  footing  courses  were  laid  to  take 
the  place  of  the  gravel  and  old  grillage,  and  the  old  stonework  relaid  by 
placing  each  course  in  its  former  position  as  nearly  as  possible.  The  pier 
was  about  80  feet  high  and  contained  about  1,100  yards  of  masonry.  The 
work  occupied  from  Sept.  15  to  Dec.  25,  1888,  and  was  done  under  the  di- 
rection of  Cecil  Frazer.  The  description  is  tiken  from  the  Engineering 
News  of  April  13,  1893. 

The  construction  of  the  piers  for  the  Philadelphia  and  Reading  railroad 
bridge  over  the  Schuylkill,  was  accomplished  by  the  use  of  a  floating  coffer- 
dam, the  foundations  being  laid  upon  the  bed  rock. 


THE   COFFER-DAM  PROCESS  FOR   PIERS. 


75 


When  in  position  for  work  the  dam  is  rectangular  in  shape,  62  feet  long 
and  36  feet  wide,  outside  dimensions,  and  16  feet  high.  Each  side  consists 
of  timber  crib  work  10  feet  wide,  making  the  inside  dimensions  42x16  feet. 
At  each  corner  there  is  a  movable  timber  extending  vertically  from  the  bot- 
tom of  the  crib  to  some  distance  above  the  top.  These  timbers  or  spuds 
are  shod  with  iron  on  the  bottom,  and  serve  to  hold  the  dam  in  position 
while  the  sheet  piling  is  being  driven.  The  dam  is  divided  vertically 


j6  THE   LOFFER-DAM  PROCESS  FOR  PIERS. 

through  each  short  side  into  two  equal  parts,  which  can  be  floated  separ- 
ately to  any  desired  position  and  afterwards  joined  together.  Watertight 
compartments  are  built  in  each  section  to  assist  in  floating  it,  and  these  com- 
partments are  also  used  to  hold  stone  when  it  is  desired  to  sink  the  cribs. 

When  the  two  sections  are  united  and  placed  in  required  position  the 
spuds  are  dropped  and  the  crib  work  is  sunk  by  letting  water  into  the  water- 
tight compartments,  and  putting  in  the  necessary  amount  of  stone. 

Any  irregularity  in  bearing  between  the  bottom  rock  and  the  bottom  of 
the  crib  is  then  corrected  by  a  diver,  who  blocks  up  where  required.  Close 
sheet  piling  of  jointed  plank  three  or  four  inches  thick  is  then  put  on  the 
outside  and  spiked  to  the  cribs.  Puddle,  composed  of  clay  and  gravel,  is 
then  thrown  around  the  bottom  outside,  and  the  dam  is  ready  to  be  pumped 
out.  When  the  masonry  reached  the  height  of  the  braces  they  were  taken 
out  and  the  dam  was  braced  against  the  masonry. 

The  maximum  depth  of  water  encountered  at  Falls  bridge  was  thirteen 
feet  at  ordinary  water  level.  Several  freshets  occurred  during  the  progress 
of  the  work  which  did  some  damage  to  the  dam.  At  one  time,  when  a  dam 
was  ready  to  be  pumped  out,  a  rise  in  the  river  moved  it  down  stream  about 
thirty  feet,  tearing  off  the  sheet  piling.  It  was  drawn  back  to  place  and 
successfully  completed.  To  make  a  complete  shift  of  the  dam  from  one 
pier  to  the  next,  with  a  gang  of  six  men,  required  about  six  or  eight  days, 
divided  as  follows :  To  take  the  dam  apart  and  reset  it,  about  three 
days  ;  to  sheet  pile,  about  two  days  ;  to  puddle,  about  one  day  ;  and  pump- 
ing, out  and  puddling  meanwhile  required  about  one  to  two  days,  'depending 
on  the  amount  of  the  leakage.  At  each  shift,  a  portion  of  the  plank  sheet 
piling,  perhaps  10  per  cent,  had  to  be  replaced  by  new  stuff.  The  pump 
tised  was  located  on  a  small  steamboat,  and  was  run  by  a  steam  engine.  The 
amount  of  pumping  required  after  the  dam  was  once  pumped  out  varied  for 
the  different  piers  ;  some  dams  required  little  pumping  and  others  a  good 
deal.  Only  one  of  the  foundations  required  much  leveling  off  of  the  river 
bed,  and  this  one  also  gave  considerable  trouble  to  keep  the  water  out,  but 
the  leaks  were  finally  stopped  by  using  gunny  bags  around  them  ;  the  bags 
being  drawn  into  the  crevices  by  the  force  of  the  water,  thus  holding  the 
puddle. 

The  floating  dam  was  used  for  the  three  piers  in  the  river  channel,  the 
two  piers  near  the  shore  being  put  in  with  ordinary  dams.  The  floating 
dam  is  still  in  good  condition  and  could  be  used  again  if  needed.  The 
original  dam  of  which  the  one  used  at  the  Falls  bridge  is  an  enlarged  copy, 
was  used  for  twenty-three  or  twenty-four  settings. 

The  foregoing  account  is  taken  from  the  Engineering  News  of  May  24, 
1S94,  the  description  being  by  W.  B.  Riegner,  who  states  also  that  the  cost 
of  the  coffer-dam,  including  one  set  of  sheet  piling,  was  $3,000,  while  the 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


total   cost  for   five   coffer-dams,    including  the  two  crib  coffer-dams  at  the 
sides  of  the  river,  was  $14,000. 

The  subject  of  subaqueous  foundations  has  been  very  fully  treated  of 
in  a  series  of  lectures  by  W.  R.  Kinipple,  M.  Inst.  C.  E.,  before  the  Royal 
Engineers'  Institute  at  Chatham,  England. 

The  use  of  six-inch  pitch  pine  close  sheeting  was  made  use  of  by  him, 
for  a  quay  wall  in  the  harbor  of  St.  Helier,  Jersey.  They  were  driven  to 
rock  or  as  deep  as  possible  with  a  2,800-pound  hammer,  and  the  tops  cut 
off  a  few  feet  beneath  half  tide  level,  and  clayey  material  banked  up 
against  the  outside.  The  bottom  through  which  the  sheet  piles  were 
driven  was  sand  and  clay. 

The  rock  was  laid  bare  to  a  depth  of  as  much  as  thirteen  feet  below 
low  water  and  in  sections  which  contained  about  900  tons  of  water  to  be 
pumped  out  ;  this  was  done  with  a  sixteen-inch  centrifugal  pump  in  about 
forty-two  minutes. 

Several  leaks  were  developed  under  the  piles,  but 
they  were  promptly  stopped  by  "stock  ramming." 
The  stock  rammer  which  is  shown  in  Fig.  55,  is  3 
inches  in  diameter,  3^  feet  long  and  banded  top  and 
bottom  with  iron.  A  ^-inch  air  hole  is  bored  up 
from  its  foot  a  distance  of  twenty  to  thirty  inches, 
and  covered  on  the  bottom  with  a  sole  leather  flap,  so 
that  air  is  let  in  and  suction  prevented  as  it  is  with- 
drawn. The  sheet  piles  have  3^ -inch  holes  bored 
through  their  sir1  as,  and  cylinders  of  clay  are  inserted 
3x9  inches  long,  similar  to  the  work  at  Sault  Ste. 
Marie.  The  stock  rammer  is  inserted  and  driven  by 
mauls  as  far  as  its  length  will  permit  when  it  is 
drawn  out,  and  other  charges  inserted  until  no  more 
clay  can  be  driven.  The  hole  in  the  pile  being  filled  with  a  wooden  plug. 

The  piers  for  the  Putney  bridge,  over  the  Thames,  were  built  by  the 
same  engineer,  with  single  pile  dams  to  a  great  depth,  by  using  fourteen- 
inch  square  piles,  with  elm  wood  tongues,  and  driving  them  down  through 
the  mud  and  clay  to  the  stiff  clay  bottom,  so  that  practically  watertight 
work  was  secured 

In  the  construction  of  the  docks  at  Victoria,  British  Columbia,  he  con- 
structed a  coffer-dam  500  feet  in  length,  in  a  depth  of  thirty-five  feet  of 
water,  the  bottom  being  of  rock  and  overlaid  in  places  with  sand  and  shells 
several  feet  in  thickness.  At  the  center  the  sand  and  shells  overlaid  a  bed 
of  clay. 

Three  rows  of  close  12xl2-inch  sheet  piling  were  driven  with  two  puddle 


iron 

coUat- 


FIG.  55— STOCK 

RAMMER. 


78  THE  COFFER-DAM  PROCESS  FOR  PIERS. 

chambers  of  seven  feet  each  between.  The  guide  piles  were  15x15  inches 
and  the  wales  were  12x12  inches. 

Where  the  dam  rested  on  rock  at  the  ends,  heavy  shoes  were  used  on  the 
piles  and  concrete  deposited  around  their  feet  to  make  the  work  watertight. 
The  dam  was  completed  in  October,  1879,  and  remained  thoroughly  tight 
until  the  dock  was  completed  over  seven  years  later. 

The  arch  bridge  at  Topeka,  Kansas,  over  the  Kaw  river,  which  is  being 
constructed  on  the  Melan  system,  of  concrete  and  steel,  by  Keepers  and 
Thacher,  the  designing  engineers,  is  a  most  interesting  piece  of  work.  The 
coffer-dams  were  required  by  the  specifications  to  be  watertight,  and  to 


FIG.  56 — TOPEKA  BRIDGE  COFFER-DAM  NO.  4. — "A"  shows  puddle  to  stop  leak. 

effect  this  4x12  inch  tongue  and  groove  sheet  piling  was  used.  The  size  of 
the  coffer-dam  for  pier  No.  4  was  18x55  feet  in  the  clear  (Fig.  56)  and  the 
piling  was  driven  about  sixteen  feet  into  the  sand  bottom  or  twenty-two  feet 
below  low  water.  The  driving  was  done  by  a  1,600-pound  hammer  with 
thirty-six  feet  leads  ;  the  power  being  furnished  by  a  15  H.  P.  hoisting 
engine. 

No  puddle  was  used  around  the  outside  except  to  stop  leaks,  and  the 
dam  was  kept  clear  of  water  with  a  No.  6  Special  Van  Wie  sand  pump. 
The  capacity  of  the  pump  was  3,000  gallons  per  minute  of  water,  and  from 
sixty  to  eighty  yards  of  sand  per  hour.  It;  was  operated  with  a  15  H.  P. 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  79 

engine.     The  other  piers  were  handled  in  a  similar  manner  and  with  no  par- 
ticular trouble. 

The  growing  scarcity  of  timber  will  doubless  lead  to  the  use  of  metal  at 
some  time  in  the  future,  to  replace  sheet  piling  for  coffer-dams,  but  where 
timber  is  abundant  and  reasonable  care  is  exercised  in  its  use,  it  will  con- 
tinue to  be  of  great  service  in  obtaining  foundations  by  this  method. 


ARTICLE   VII. 

THE    COFFER-DAM    PROCESS    FOR    PIERS.* 

METAI,    CONSTRUCTION. 

HIN  steel  shells  have  been  used  extensively  for  foundation  work,  but 
in  the  majority  of  cases  they  have  been  retained  as  essential  fea 
tures  of  the  permanent  construction. 

This  is  more  particularly  the  case  in  locations  where  stone  is 
scarce  or  expensive  and  it  becomes  necessary  to  substitute  some 
other  material    for    foundations.      Tubular  steel    piers    are    con- 
structed   of  two  tubes,  ranging  from  24  inches  to  several  feet  in 
diameter,  or  in  the  case   of  pivot  piers,  from  15  feet,  with  a  single  tube 
for  a  pier,  to  30  leet  or  more. 

In  a  number  of  instances  the  steel  shells  for  ordinary  piers  have 
been  made  oblong,  in  the  general  form  of  a  stone  pier,  and  braced  internally 
to  hold  them  in  shape  during  sinking,  after  which  they  are  filled  with 
concrete. 

The  metal  shells  for  the  Hawkesbury  bridge  in  Australia  were  of  this 
character,  20  feet  wide,  48  feet  long  and  with  rounded  ends.  Each  one  was 
provided  with  three  dredging  wells,  each  8  feet  in  diameter,  through  which 
the  dredges  shown  in  the  view  (Fig.  57)  were  operated.  While  these  piers 
were  not  used  as  coffer-dams,  they  were  made  water-tight  by  boiler  riveting, 
so  that  by  pumping  water  in  and  out  the  displacement  could  be  kept  con- 
stant, and  in  this  way  control  the  pier  in  an  average  tide  of  five  feet.  These 
piers  were  sunk,  by  dredging  out  the  material  from  the  inside,  to  the  great 
depth  of  from  135  feet  8  inches  to  197  feet  below  the  pier  tops,  or  a  distance 
of  155  feet  below  low  water. 

Both  inclined  and  vertical  cutting  edges  were  used,  with  the  result  that 

*  Metal  caissons  have  been  used  much  more  frequently  in  this  country  than  have  metal 
'  offer-dams,  the  reason  being  the  cheapness  of  timber  and  its  more  easy  application. 

In  England  metal  coffer-dams  are  more  frequently  used.  The  example  given  in  this 
article — the  Forth  bridge  coffer-dams — might  have  been  supplemented  by  reference  to  those 
used  on  the  Clarence  bridge  at  Cardiff,  the  construction  used  being  illustrated  and  described 
in  Engineering,  and  is  especially  notable  for  the  design  of  the  bracing. 

80 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


81 


the  inclined  ones  were  of  frequent  trouble  and  the  vertical  ones  none  what- 
ever. 

"If  it  is  essential  to  increase  the  bearing  surface  at  the  bottom  of  the 
caisson  to  an  area  which  is  not  required  in  the  upper  portion,  this  end  can 
be  secured  by  a  vertical  cutting  shoe  of  considerable  height,  with  a  step  or 
steps  into  the  smaller  diameter.  This  is  quite  as  efficient  to  secure  the  end 
in  view  as  a  long  incline  on  the  cutting  shoe,  and  has  decided  advantages. 
In  the  denser  material  the  vertical  sides  leave  the  ground  undisturbed  for 
some  height  close  to  the  skin  of  the  caisson,  and  a  vertical  guide  is  secured 


riG.  57. — HAWKESBURY  BRIDGE. — Caisson  No.  6  in  Process  of  Sinking,  Showing 
Excavator  and  Shore  Chains  for  Maintaining  Vertical  Position. 

which  is  entirely  wanting  in  the  case  of  an  inclined  shoe.  This  guide  is 
valuable  in  cases  where  the  soil  may  differ  in  density  under  the  shoe,  and 
particularly  so  if  the  excavation  has  been  carried  too  far  below  the  bottom 
of  the  shoe.  With  an  inclined  shoe  and  a  slip  of  soil  into  the  dredging 
well  from  one  side  more  than  another,  experience  in  deep  dredging  has 
shown  that  there  is  a  decidedly  greater  tendency  to  a  horizontal  movement 
than  with  a  vertical  shoe.  The  former  has  a  flare  to  direct  this  sidewise 
motion  in  the  first  place,  and  nothing  but  a  certain  amount  of  disturbed 
material  above  the  shoe  to  resist  this  tendency." 

The  above  account  is  from  the  Engineering  News  of  January  5,  1889, 


82 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


the  work  having  been  done  under  the  direction  of  J.  F.  Anderson,  of  the 
firm  of  Anderson  &  Barr.  The  shells  were  filled  with  concrete  up  to  low 
water  and  masonry  built  from  low  water  up  to  the  top  of  the  piers. 

Such  work  may  be  made  water-tight  by  riveting  according  to  ordinary 
boiler-maker  rules,  or  if  extra  thick  plates  are  used  this  can  be  exceeded 
and  the  rivets  spaced  some  farther  apart.  The  joints  may  be  made  with 
ordinary  laps  and  calked,  or  a  very  much  better  appearance  may  be  obtained 
by  the  use  of  butt  joints,  and  if  desirable  to  avoid  calking,  then  a  calking 
strip  may  be  used  to  make  the  joints  tight.  This  is  merely  a  cloth  or 
canvas  strip,  thoroughly 
saturated  with  paint  paste, 
and  is  laid  between  the 
metal  surfaces,  and  the 
riveting  draws  the  plates 
upon  it  and  a  tight  joint 
will  result.  The  shells  will 
be  filled  with  concrete  as 
soon  as  the  piers  are  in 
place  and  the  foundation 
prepared,  so  that  only  a 
temporary  use  is  required 
of  the  strip. 

When  metal  cylinders 
are  used  simply  as  casings 
for  concrete  they  need  not 
be  made  water-tight, as  they 
can  be  dredged  out  and 
have  the  concrete  deposited 
through  the  water.  The 
metal  should  never  be  less 
than  one-quarter  inch  in 
thickness,  and  on  first-class 

work  five-sixteenths  to  one-half  inch  is  preferable.  Railroad  work  of  this 
character  is  usually  constructed  of  three-eighths  inch  metal  for  ordinary 
depths. 

The  pivot  pier  of  the  bridge  over  the  Little  Bras  d'Or  river  in  Cape 
Breton  was  constructed  of  seven  metal  cylinders  braced  together.  The  cen- 
ter tube  was  4  feet  in  diameter,  while  the  six  outside  cylinders  were  3  feet 
in  diameter.  (Fig.  58).  The  center  pivot,  about  which  the  span  revolves, 
rests  on  the  center  tube,  while  the  track  is  supported  by  the  other  tubes, 
but  resting  directly  on  rolled  beams  covered  with  three-eighths  inch  plate. 

The  tubes  rest  on  a  clump  of  piles,  cut  off  at  the  bed  of  the  stream,  with 


FIG.  58.— GROUP  OF  CYLINDERS  FOR  PIVOT  PIERS. 


COFFER-DAM  PROCESS  FOR  PIERS. 


one  pile  extending  up  into  the  center  of  each  tube  about  six  feet,  around 
which  the  concrete  was  deposited,  thus  preventing  displacement.  Concrete 
and  stone  were  placed  on  the  outside  up  to  15  feet,  as  a  protection. 

This  work  was  described  by  Martin  Murphy. in  Trans.  Am.  Soc.  C.  E., 
Vol.  29,  who  also  describes  a  pier  for  the  Victoria  bridge,  over  Bear  river, 
constructed  with  two  tubes,  resting  on  piles  cut  off  at  the  bed  of  the  stream, 
but  having  four  piles  inside  each  tube.  (Fig.  59.)  Around  the  outside  are 
timber,  concrete  and  broken  stone  as  a  protection.  The  saw  used  for  cut- 
ting off  the  piles  under  the  water  was  very  much  simpler  than  the  one 
shown  in  Fig.  35,  and  is  illustrated  in  Fig.  60. 

Cylinder  piers  on  European  work  are  often  of  very  elaborate  construc- 
tion. The  bridge  on  the  Aa,  at  the  crossing  of  the  Russian  Riga-Orel  rail- 
way, is  supported  on  elegant  cylinder  piers,  with 
moulded  caps,  steel  cut-waters,  and  are  braced 
together  with  cylinders  transversly.  (Fig.  61.) 
This  forms  a  very  efficient  construction,  but  so 
expensive  to  manufacture  that  it  is  usually  re- 
placed by  bracing  of  struts  and  rods,  as  in  Fig. 
59,  or  by  a  metal  diaphragm  (Fig.  62),  stiffened 
with  angles. 

Cylinders  of  water-tight  construction  and  of 
large  diameter  may  be  used  as  coffer-dams,  where 
they  are  sunk  into  impervious  strata,  or  by 
sealing  them  with  concrete  around  the  bottom 
where  they  are  placed  upon  smooth  rock  bottom. 
In  the  construction  of  light-houses  such  cylinders 
have  been  placed  upon  clean  rock  bottom  through 
from  12  feet  to  18  feet  of  water  and  concrete 
deposited  around  the  circumference  of  the  base 
outside  and  inside  to  make  them  water-tight, 
after  which  they  were  pumped  out  and  the  foun- 
dation laid. 

To  withstand  the  pressure  of  any  considerable  depth  of  water  the  thick- 
ness and  strength  should  be  calculated  and  the  construction  carefully 
designed.  Unless  the  depth  of  water  exceeds  ten  feet,  or  the  diameter  of 
tube  exceeds  six  feet,  the  minimum  thickness  it  is  advisable  to  use,  will  be 
sufficient  for  strength. 

This  refers  only  to  quiescent  pressure,  and  any  shock  must  be  carefully 
considered  and  taken  account  of,  by  interior  bracing  if  necessary. 

The  most  thorough  discussion  of  the  strength  of  thin,  hollow  metal 
cylinders  is  given  in  "  Elasticitat  and  Festigkeit,"  by  C.  Bach.  This  con- 
siders the  cylinder  to  have  sides  of  a  greater  thickness  than  is  true  with 


FIG.  59. — PIER   OF   TWO   CYLIN- 
DERS, VICTORIA  BRIDGE. 


84 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


pier  shells,  and  having  one  radius  given,  the  radius  to  the  other  side  of  the 
plate  is  found  from  the  formula,  the  stress  being  variable  from  the  inside  to 
the  outside  of  the  plate. 

For  thin  cylinders  the  stress  may,  without  appreciable  error,  be  assumed 
to  be  uniform  over  the  cross  section  of  the  plate,  and  the  thickness  t  in 
inches  be  found  from  the  formula 

t—  .001  r  h 
where  r  is  the  radius  of  the  cylinder  in  feet  and  h  is  the  depth  of  the  water 


foundation   Pi/ing  for 
Victoria.  Bridge 


JL 

iflhl 

i 

nr 

t 

O 

•  - 

--16' 

0-- 

- 

> 

CwJ 

2tf 

j 

, 

Jd 

V-,' 

J6V/d. 

L  L 

r      n 
j        i 

u  L 

-i=  =r 
1 
1 
U 

n 
i 

UA 

1               ' 
1               | 
J             J 

1        ! 

i      J 

j, 

r^ 

L. 
1 

^h 

JjS-w^p 

J         ^v 

|r—  =-  =r   ===•=-  ='  = 

FIG.   60. — CIRCULAR   SAW   FOR   CUTTING   OFF   PILES  UNDER   WATER. 

to  the  section  in  feet,  and  t  in  no  case  to  be  used  less  than  one-quarter  incn 
in  thickness. 

This  is  on  the  assumption  that  the  metal  will  stand  5,000  pounds  per 
square  inch  in  compression  with  safety.  For  large  cylinders,  or  for  rec- 
tangular shells,  girders  and  stiffeners  or  ties  and  struts  must  be  added  to 
prevent  distortion. 

The  foundations   for  the  great  Forth  Bridge,  which  were  constructed 


86 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


under  the  direction  of  Sir  John  Fowler  and  Sir  Benjamin  Baker,  required 
the  use  of  various  methods  to  reach  solid  bearing,  as  the  enormous  weight 
to  be  carried  required  the  most  substantial  piers  obtainable. 

The  use  of  coffer-dams  of  metal  for  the  Inchgarvie  piers  is  described  by 
Engineering:  The  site  of  the  two  north  or  shallow  piers  being  wholly  sub- 
merged at  high  water,  and  about  half  in  the  case  of  the  northeast  and  three- 
fourths  in  the  case  of  the  northwest  pier,  submerged  also  at  low  water,  the 

preliminary  work  was 
tidal,  and  between  spring 
tides  no  work  could  be 
carried  on  at  all  at  this 
place.  When  it  is  con- 
sidered how  exposed  the 
position  was  there — the 
work  having  to  be  car- 
ried on  upon  a  narrow 
ledge  of  rock  attacked 
by  wiiid  and  waves  from 
all  sides — it  will  be  un- 
derstood that  the  pro- 
gress could  not  be  very 
rapid.  The  conditions 
of  the  contract  here  re- 
quired that  the  rock 
should  be  excavated  in 
steps,  and  that  the  rub- 
ble masonry  comprising 
the  foundation  of  the  cir- 
cular granite  piers  (Fig.  63)  should  be  bound  by  an  iron  belt  60  feet  in 
diameter  and  3  feet  deep;  the  highest  portion  of  the  rock  upon  which 
this  belt  rested  to  be  2  feet  below  low  water;  the  belt,  or  at  any  rate  a  part 
of  it,  to  be  brought  down  to  form  a  protection  for  the  foundation  rubble 
masonry  upon  the  lower  steps. 

It  was  therefore  decided  to  cut  a  chase  8  feet  wide  (3  feet  to  the  inside 
and  5  feet  to  the  outside  of  the  60  feet  circle)  out  of  the  rock  where  it  was 
higher  than  2  feet  below  low  water,  to  make  the  60  feet  belt  of  three  thick- 
nesses of  one-half  inch  plate  and  to  carry  the  center  plate  downward,  after 
it  had  been  cut,  in  such  a  manner  as  to  fit  as  nearly  as  possible  the  natural 
contour  of  the  rock.  (Fig.  64 A.)  A  light  staging  was,  therefore,  erected 
above  high  water,  the  correct  center  of  the  pier  placed  upon  it,  and  by 
means  of  a  trammel-rod  30  feet  in  length,  from  the  end  of  which  a  pointed 
sounding-rod  was  suspended,  a  correct  reading  was  taken  every  6  inches  on 


FIG.    62. — CYLINDER    PIERS,    WITH    DIAPHRAGM. 


OF  THK 

UNIVERSITY 


87 


COFFER-DAM  PROCESS  FOR 


the  circumference  of  the  60  feet  circle,  after  a  diver  had  been  around  to 
clear  out  any  loose  stones  lying  in  the  line,  or  picking  off  any  sharp  points 
projecting.  These  readings  were  plotted  and  the  center  plates  cut  to  it. 
In  the  meantime  work  had  been  done  upon  the  chase;  and,  when  nearly 
cut  down  to  the  right  level,  the  belt  was  put  together  on  the  staging  exactly 
above  the  site  of  the  pier.  The  plates,  projecting  downward  and  forming 
the  shield,  were  stiffened  by  I  bars  vertically  over  the  butts,  and  where 
required  to  be  carried  down  to  a  considerable  depth,  as  in  the  case  of  the 
northwest  pier,  they  were  further  stiffened  by  horizontal  circular  girders 
and  stayed  to  the  rock  by  bars  of  angle  iron.  The  whole  belt  was  now 
riveted  up,  and  when  ready  received  two  coats  of  red  lead  paint,  and  was 
lowered  down  to  position  by  means  of  hydraulic  jacks.  (Fig.  64B.)  The 
top  edge  of  the  3  feet  belt  was  then  leveled  all  round,  and  corrected  where 


FIG.    63. — CIRCULAR   GRANITE   PIER   AS   FOUNDED    BY    COFFER-DAM.      FORTH    BRIDGE. 

necessary.  A  heavy  angle  iron  6  inches  by  6  inches  by  J/Q  inches  ran 
round  the  inside  of  the  3  feet  belt,  and  upon  this  was  now  set  a  single  tier 
of  temporary  caisson,  10  feet  in  height, .and  consisting  of  fourteen  segments 
of  about  30  cwt.  each  in  weight.  This  helped  to  keep  the  belt  down  to  the 
rock,  and  a  number  of  heavy  blocks  of  stone  were  placed  on  the  top  of  the 
caisson  for  the  same  purpose.  A  sluice  door  in  the  lower  part  was  kept 
open  to  admit  of  the  tide  flowing  in  and  out. 

Steps  were  now  taken  to  make  good  the  joint  between  the  3  feet  belt  and 
the  shield  and  the  bed-rock.  This  was  done  in  the  following  manner  :  A 
number  of  concrete  bags,  about  14  inches  by  30  inches,  and  8  inches  to  9 
inches  thick,  were  prepared  and  passed  down  to  a  diver,  who  laid  them 
round  the  outside  of  the  belt  at  a  distance  of  about  4  inches.  A  second 
row  was  next  laid  round  the  outside  of  the  first  row,  and  tolerably  close  up, 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


the  space  between  the  two  being  made  up  by  clay  puddle  well  stamped 
down.  Any  split  or  hole  or  crevice  in  the  rock  was  also  filled  with  clay. 
Upon  these  two  lower  rows  other  bags  were  now  laid  crosswise  ;  upon  these, 
two  rows  lengthwise,  and  a  fourth  row  crosswise  on  the  top,  which  was 
laid  close  up  to  the  belt.  This  was  done  in  sections  of  about  15  feet  to  16 
feet  length  all  along  the  shield,  but  round  the  outside  of  the  treble  belt  only 
two  bags  deep  were  laid.  On  the  inside  also  a  single  row  of  clay  bags, 


AI.IV.  IROH 

Section  Through  Shield 
cS/miv/rvgMocte  of  Aiding  Joint  to  RocK 


Cone,  bags  loaded 
ly/tA  sane/  bags. 

Cement  groi/t. 


w 

I  ROM  COFFER-DAM .  //.  IV.  PIER-* 
Outside    View  o/c5/i/e/c/. 

FIG.   64.  — FORTH    BRIDGK.       METAL    COFFER-DAM. 

backed  by  a  row  of  concrete  bags,  and  loaded  with  stones,  was  laid  round 
the  complete  circle.  Cement  grout,  without  intermixture  of  sand,  was  now 
prepared  and  passed  down  to  the  diver — but  only  at  slack  tide,  high  water 
or  low  water — who  lifted  off  one  or  more  of  the  top  bags  and  poured  the 
grout  into  the  narrow  space  left,  until  it  overflowed.  He  then  replaced  the 
bag  and  proceeded  to  the  next  division,  until  all  was  done.  Forty-eight 
hours  were  allowed  to  elapse  for  the  setting  of  the  cement ;  the  sluice  valve 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  89 

was  then  closed  and  the  caisson  pumped  out  gradually.  When  leaks  were 
discovered  the  diver  descended  to  examine  the  outside,  and  where  neces- 
sary, cut  out  some  of  the  grouting  and  replace  it  by  new. 

As  it  was  not  considered  that  this  cement  joint  would  be  able  to  stand 
the  full  pressure  of  the  tidal  rise  the  coffer-dam  was  worked  as  a  half  tide 
one,  it  having  to  be  pumped  out  every  tide  as  soon  as  the  water  had  fallen 
below  the  top  edge  of  the  temporary  caisson.  In  addition  to  the  hydro- 
static water  pressure,  the  caisson  had  to  stand  the  heavy  seas  thrown 
against  it,  whether  coming  from  east  or  west.  Under  these  circumstances 
it  was  often  considered  advisable  not  to  pump  out  the  coffer-dam,  but  leave 
the  sluices  open  and  allow  the  tidal  flow  free  access.  Under  such  condi- 
tions it  will  be  easy  to  see  that,  during  a  season  of  bad  weather,  much  delay 
could  not  be  avoided,  and  though  the  work  of  excavation  had  been  com- 
menced in  the  summer  of  1883  it  was  not  till  the  middle  of  April  of  the 
following  year  that  the  first 'rubble  masonry  could  be  laid  in  this  pier.  In 
working  the  excavation  no  blasting  was  done  within  one  and  a  half  feet  of 
the  iron  belt,  but  the  rock  was  quarried  up  to  within  6  inches  and  the  rub- 
ble then  built  in  at  once.  Any  steps  cut  in  the  deeper  portion  were  invar- 
iably at  least  twice  as  broad  as  they  were  deep.  The  deepest  point  to 
which  the  excavation  had  to  be  carried  in  this  pier  was  8  feet  below  low 
water. 

The  coffer-dam  or  caisson  for  the  northwest  pier,  Inchgarvie,  was  done 
in  the  same  way  precisely  as  described  for  the  northeast,  only  that  owing 
to  the  experience  gained  by  the  divers  and  other  men  engaged  upon  the 
work  the  progress  was  much  more  rapid. 

In  the  northwest  pier  the  depth  of  the  shield  was  15  feet  below  low 
water,  and  extended  to  nearly  one-half  of  the  circumference.  There  was, 
therefore,  in  addition  to  the  vertical  I  bars  which  covered  the  butt  joints 
of  the  shield  plates,  three  horizontal  circular  girders,  carried  at  a  distance 
of  4  feet  6  inches  from  each  other,  and  from  these  a  number  of  horizontal 
tie  bars  with  cross-bars  at  the  ends  were  carried  radially  and  level  to  the 
rock  opposite  and  pinned  to  it,  and  afterward  built  into  the  solid  rubble 
masonry.  (Fig.  64B.) 

This  mode  of  making  the  joint  between  the  rock  and  the  iron  belt  was 
simple  and  quite  effective.  Most  of  the  leaks  were  due  to  natural  crevices 
in  the  rock,  running  from  the  inside  to  the  outside  at  a  considerable  depth. 
These  were  circumvented  by  building  small  clay  dams  round,  and  leading 
the  water  by  a  chute  to  the  pump.  Leaks  were  also  caused  by  the  action 
of  heavy  waves  running  up  to  the  temporary  caisson  at  low  water  with 
great  violence,  and  shaking  the  whole  fabric. 

The  whole  of  the  northeast  pier  was  built  in  a  half-tide  caisson,  as  the 
work  was  not  pressing ;  but  in  the  case  of  the  northwest  pier,  so  soon  as  the 


9o 


THE  COFFER-DAM  PROCESS  FOR  i°IERS. 


rubble  masonry  inside  had  been  brought  up  to  low  water  level  a  second  tier 
of  temporary  caisson  was  added,  and  the  work  could  then  be  carried  on  at 
all  states  of  the  tide.  While  tidal  work  was  carried  on  in  these  two  coffer- 
dams the  amount  of  water  which  had  to  be  pumped  out  every  tide  was 
250,000  gallons  in  the  one  case  and  340,000  in  the  other.  The  time  occu- 
pied was  50  to  55  minutes,  but  work  was,  of  course,  commenced  so  soon  as 
the  higher  parts  were  laid  dry.  For  pumping  out  smaller  quantities  of 
water  collected  through  leaks,  pulsometers  or  small  centrifugal  pumps 
were  used. 

An  exterior  view  of  the  work  is  shown  in  Fig.  65,  and  while  the  method 


FIG.    65. — FORTH    BRIDGE,    CIRCULAR   GRANITE    PIER    AND    METAI,    COFFER-DAM. 

was  successful  and  worthy  of  much  study,  the  expense  would  only  be 
justifiable  where  the  metal  would  be  retained  as  part  of  the  permanent 
foundation,  which  was  the  case  on  this  work. 

In  man}7  cases  such  a  shell  could  be  designed  of  the  proper  size  for  the 
footing  course,  and  after  use  as  a  coffer-dam  in  obtaining  the  foundation  it 
could  be  filled  with  concrete  and  serve  as  a  base  for  the  pier.  Being  made 
in  sections  vertically,  portions  projecting  above  low  water  could  be  removed 
and  used  on  still  other  piers. 

Metal  sheet  piles  are  seldom  used  for  any  class  of  work,  and  need  not  be 


THE  COFFER-DAM  PROCESS  FOR  PIERS,  91 

discussed  at  length  in  this  connection.  On  some  harbor  work  at  Cuxhaven 
Harbor,  Germany,  hollow  metal  sheet  piles,  of  elongated  elliptical  section, 
were  used,  and  after  being  driven  were  filled  with  concrete. 

Whatever  the  class  and  form  of  material  it  may  be  decided  to  use,  in 
securing  a  foundation  bythe  coffer-dam  method,  the  temporary  construction 
should  be  so  related  to  the  permanent  foundation  that  as  much  as  possible 
of  the  material  used  and  labor  employed  will  be  of  service  in  the  finished 
structure. 


ARTICLE    VIII. 

THE    COFFER-DAM    PROCESS    FOR    PIERS.* 

PUMPING   AND   DREDGING. 

HE   degree  of  success    which   has  been  attained   in   the   building  of  a 

coffer-dam  will  be  evident  when  the  pumping  process  is  begun.  After 
having  been  pumped  out,  if  the  leakage  is  so  small  as  to  require  only  a  small 
amount  of  pumping  to  keep  it  free  from  water,  it  may  reasonably  be  consid- 
ered a  success. 

The  pumping  should  not  exceed  what  can  be  done  by  a  steam  siphon,  a 
small  pulsometer,  or  by  running  a  centrifugal  pump  intermittently.  Should 
leaks  develop  which  cannot  readily  be  contended  with,  then  repairs  must  be 
made. 

The  use  of  pumps  for  this  class  of  work  on  ancient  bridges  is  described 
by  Cresy.  The  bascule,  used  by  Perronet  at  the  bridge  of  Orleans  (Fig.  66), 
is  one  of  the  most  primitive  forms.  It  consists  of  a  see-saw  apparatus,  at  each 
end  of  which  ten  men  were  placed,  and  150  motions  were  given  it  in  each  quar- 
ter of  an  hour.  Four  cubic  feet  of  water  were  raised  three  feet  each  time,  or 
about  300  gallons  per  minute.  Various  other  kinds  of  pumps  were  used  at 
this  bridge,  among  them  the  chapelet,  which  is  similar  to  a  modern  chain 
pump,  worked  by  hand.  Then  the  same  device  was  employed,  but  geared 
to  be  operated  by  horses  on  a  platform.  A  chapelet  operated  by  a  water 
wheel  was  also  used  (Figs.  67  and  68).  The  large  wheel  had  124  cogs, 
while  the  pinion  had  15,  which  caused  the  raising  of  over  sixty-six  buckets 
on  the  chain  for  each  turn  of  the  large  wheel.  At  180  turns  of  the  wheel 
per  hour,  with  each  bucket  lifting  290  cubic  inches  of  water,  the  capacity 
was  about  250  gallons  per  minute. 

A  great  bucket  wheel  was  employed  by  the  same  engineer  at  the  Neuilly 
bridge,  16  feet  6  inches  in  diameter,  4  feet  6  inches  wide,  with  sixteen 
buckets. 

*  Attention  is  called  to  the  numerous  references  in  other  articles  of  the  pumping  plants 
actually  employed  on  coffer-dams,  and  especially  to  the  plant  used  at  Topeka,  page  78. 

Great  care  should  always  be  given  to  the  selection  of  a  pumping  plant  of  the  proper  type 
and  proper  size,  as  the  statements  regarding  capacity  are  often  misleading.  The  outfit 
should  be,  if  needed,  one  able  to  take  care  of  the  dredging,  if  the  material  is  such  that  it  can 
be  pumped. 

92 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


93 


FIG.  66. — OI<D  BASCUIvE  PUMP. 


The  pumps  used  at  the  present  time  on  very  small  work  are  usually 
square  wooden  box  lift  pumps,  such  as  are  used  on  large  river  barges,  and 
are  worked  by  one  or  more  men  lifting  on  a  plunger.  These  are'  often 
replaced  by  a  similar  pump  of  metal  (Figs.  69  and  70)  with  a  tube  of  gal- 
vanized metal,  and  often  spiral  riveted. 
The  one  shown  in  Fig.  69  has  the  top 
and  bottom  soldered  to  the  tube,  while 
the  one  in  Fig.  70  has  screw  joints.  The 
cost  of  a  4-inch  pump  eight  feet  long 
with  fixed  top  and  bottom  would  be  about 
$6,  while  the  screw  joints  would  about 
double  the  cost. 

Such  pumps  are,  however,  little  used, 
as  the  labor  becomes  excessive  where 
there  is  any  quantity  of  water  to  deal 
with,  and  diaphragm  pumps  (Fig.  71) 
are  employed,  which  work  on  a  rubber 
diaphragm,  in  place  of  a  piston  and 
plunger,  and  throw  a  large  amount  of 
water,  besides  allowing  the  passage  of 

sand  and  gravel  without  choking  the  pump.  The  2  Y?.  -inch  suction  has 
a  capacity  of  twenty-five  gallons  per  minute,  and  the  3-inch  suction 
of  fifty-eight  gallons  per  minute,  the  list  price  of  the  two  sizes  being  $20  and 
$26,  respectively;  the  maximum  lift  of  the  pump  being  thirty  feet. 

Where  steam  can  be  obtained  steam  siphons  are  often  used,  the  steam 
being  introduced  into  the  main  pipe  through  a  nozzle,  thus  causing  a  suction, 
which  with  a  3-inch  discharge  Van  Duzen  jet  will  deliver  7,200  gallons  of 
water  per  hour,  the  height  of  the  pump  above  water  being  11  feet,  the  point 
of  discharge  being  19  feet  above  the  pump,  making  a  total  lift  of  30  feet. 
This  size  will  require  an  18-horse  power  boiler  and  a  steam  pressure  of  fifty 
pounds.  The  suction  pipe  is  one  inch  larger  than  the  discharge,  while  the 
steam  pipe  is  1#  inches  in  diameter,  with  a  jet  opening  of  about  |f  inches. 
The  list  price  of  a  pump  of  this  size  (Fig.  72)  is  $36,  the  piping  being 
extra.  The  pump  is  constructed  of  gun  metal  and  will  last  indefinitely. 
The  strainer  should  always  be  used  and  will  cost  about  $4  extra  for  the 
4-inch  pipe.  The  piping  should  have  long  bends  in  place  of  elbows  where 
a  turn  is  required. 

This  make  of  pump  is  manufactured  from  ^-inch  discharge,  with  a 
capacity  of  200  gallons  per  hour,  up  to  5-inch  discharge  with  a  capacity  of 
12,000  gallons  per  hour.  The  smaller  sizes  are  useful  for  priming  centrif- 
ugal pumps  and  for  a  variety  of  uses  around  a  contractor's  plant. 

The  Lansdell  siphon  pump  (Fig.  73)  has  a  double  suction  C  C,  to  which 


94 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


rubber  suction  pipes  are  attached.  The  steam  pipe  is  attached  to  B,  and 
when  the  steam  is  turned  on  it  is  blown  across  A  and  through  D,  thus  ex- 
hausting the  air  from  the  chamber  A.  Water  rises  through  C  C  by  atmos- 
pheric pressure  to  fill  the  vacuum,  and  it  is  forced  out  through  D  by  the 
steam,  the  velocity  being  proportional  to  the  steam  pressure.  The  steam 


FIG.  67. — OLD  CHAPELET,   SIDE  ELEVATION. 

supply  should  be  as  close  to  the  pump  as  possible,  to  prevent  condensation, 
and  the  turns  in  the  pipe  should  be  easy  bends,  as  stated  regarding  the  Van 
Duzen  jet.  When  the  height  exceeds  fourteen  feet,  to  which  the  water  is  to 
be  pumped,  the  suction  pipes  must  be  long  enough  to  allow  the  center  of 
the  pump  to  be  placed  fourteen  feet  above  the  water.  With  a  3-inch  dis- 
charge, a  \yz -inch  steam  pipe  is  required  and  a  12-horse  power  boiler.  With 
a  6-inch  discharge  a  2^ -inch  steam  pipe  is  required  and  a  50-horse  power 
boiler. 

The  rated  capacity  of  the  3-inch  is  450  gallons  per  minute,  of  the  6-inch 
1,800  gallons.     But  this  would  likely  not  be  realized  in  practice. 

The  vacuum  pump  which  has  reached  the  most  general  adoption  is  the 
Pulsometer,  and  is  in 
many  ways  better  adapt- 
ed to  light  service  than 
a  centrifugal  pump  of 
small  size.  There  are 
no  bearings  to  keep  up, 
no  belts  to  keep  tight, 
and  no  trouble  in  pre- 
paring a  foundation,  as  FIG.  68. — OLD  CHAPBLET,  END  ELEVATION. 
the  pump  is  suspended 

by  the  hook  shown  in  Fig.  74.  The  pump  is  operated  by  admitting 
tht  steam  through  the  pipe  at  the  extreme  top  (Fig.  75),  the  pump  having 
been  previously  primed  by  filling  the  middle  chamber  with  water.  The  air 
valves  are  closed  and  the  steam  passes  into  the  right  hand  chamber  A 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


95 


FIG.  69. — HAND 

PUMP. 
SOLDERED  JOINTS. 


FIG.  70. — HAND 

PUMP. 
SCREW  JOINTS. 


clearing  it  of  water  by  forcing  it  into  the 
discharge  chamber  shown  in  dotted  lines. 
The  steam  then  condenses  at  once  and 
the  ball  C  changes  its  seat,  closing  the 
right  hand  and  opening  the  lett  hand 
chamber  to  the  steam.  The  vacuum, 
formed  by  the  bteatn  condensing  in  the 
right  hand  chamber  A,  allows  it  to  fill 
with  water  by  atmospheric  pressure 
through  the  suction  pipe  at  the  extreme 
bottom  and  through  the  chamber  D,  it 
being  retained  by  the  valves  E  E.  The 
steam  then  enters  the  left  hand  cham- 
ber A  and  the  operation  is  repeated. 
The  chamber  J  is  a  vacuum  chamber. 

In  starting  the  pump  the  steam  is 
turned  on  for  three  or  four  seconds,  then 
shut  off  for  four  or  five  seconds,  alternat- 
ing these  movements  until  the  pump  is 
started.  The  steam  is  then  turned  on 

about  half  or  three-quarters  of  a  revolution,  the  two  side  air  valves  opened 

about  half  a  turn,  and  then  the  middle  air  valve  opened   slowly  until  a 

regular  stroke  is  obtained. 

The    capacity  of  the    3-inch   dis- 
charge, with  a  3^ -inch  steam  pipe  and 

operated  by  a  9-horse  power   boiler,  is 

180  gallons  per  minute  when  the  lift 

is  as  much   as  twenty- five  feet;  and 

for  the  6-inch  discharge,  with  a  1^- 

inch   steam  pipe  and  operated    by   a 

35-horse  power   boiler,    1,000  gallons 

for  the  same  lift. 

The    pulsometer     is     remarkably 

smooth  in  operation,  and   except    for 

the   slight  click   of  the  ball  and   the 

discharge  of  water  in  a  steady  stream, 

one  would  scarcely  know  it  was  pump- 
ing.    Where    a    good-sized    hoisting 

engine  boiler  is  in  use  on  foundation 

work,   it   can  be  used   to   supply   the 

steam  for  pumping.     The  work  illus- 

trtaed  in   Fig.    4   was   easily   kept   free   of  water  by  a  small  pulsometer. 


FIG.    71. — DIAPHRAGM    PUMP. 


96 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


while  its  use  has  been  cited  in  a  number  of  cases  where  the  coffer- 
dam was  pumped  out  by  a  centrifugal  pump,  and  then  the  leak- 
age kept  under  control  by  a  medium  sized  pulsometer,  which  required  but 
little  attention.  The  pump  should  be  provided  with  a  strainer  at  the  bottom 
of  the  suction  pipe,  all  the  connections  must  be  air  tight,  no  sharp  bends 
should  be  made  in  the  pipe,  and  with  dry  steam  successful  working  will 
result.  Another  pump  of  similar  construction  is  the  Maslin  Automatic 
Vacuum  Pump,  which  differs  from  it  in  important  details.  What  has  been 
said  regarding  the  pulsometer  will  apply  as  well  to  the  Maslin  pump. 

All  the  foregoing  devices  are  for  use  where  the  amount  of  water  to  be 
handled  in  a  given  time  is  of  limited  amount,  but 
where  large  quantities  are  to  be  pumped  out  of  coffer- 
dams in  short  periods  of  time,  resource  must  be  had 
to  centrifugal  pumps,  which  have  reached  a  high 
state  of  perfection.  Where  the  water  is  to  be  lifted 
ten  feet  an  ordinary 
(reciprocating  pump 
would  exhibit  an 
efficiency  of  only 
30  per  cent,  while 
a  centrifugal  pump 
would  have  an  effi- 
ciency of  64  per 
cent.  For  a  lift  of 
seventeen  feet  the 
reciprocating  type 
would  have  an  effi- 
ciency of  50  per 
cent,  while  the 
centrifugal  would  1 
reach  its  maximum 
of  69  per  cent  effi- 
ciency, dropping  to 
only  50  per  cent  for 
a  lift  of  fifty  feet,  while  the  other  type  would  increase  to  75  per  cent. 
From  this  it  will  be  seen  that  the  centrifugal  pump  is  essentially  a  low  lift 
machine. 

Actual  tests  of  pumps  show  that  the  maximum  results  are  very  seldom 
realized,  a  9-inch  discharge  of  one  make  showing  an  increase  from  46.52  per 
cent  for  a  12.25  feet  lift,  to  57.57  per  cent  for  a  13.08  lift;  while  another 
make  of  10-inch  discharge,  shows  a  decrease  from  64.5  per  cent  for  a  12.33 
lift,  to  55.72  per  cent,  for  a  13  feet  lift.  The  greatest  efficiency  at  hand  is 


FIG.  72. — VAN  DUZEN 
JET   PUMP. 


FIG.   73.   I.ANSDEXI/S 
SYPHON  PUMP. 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


97 


shown  by  a  German  pump  with  a  9^- 
inch  discharge,  a  10.3-inch  suction,  and 
a  20.5-inch  disk,  running  at  500  revolu- 
tions. The  lift  was  16.46  feet  and  the 
efficiency  73.1  per  cent! 

That  such  results  are  not  realized  on 
actual  work  is  readily  understood  when 
it  is  considered  what  little  care  is  used 
to  properly  place  and  operate  such  a 
plant,  how  little  attention  is  paid  to 
having  a  proper  boiler  and  engine,  and 
what  lack  of  care  there  often  is  to  keep 
the  plant  in  good  repair. 

An  ideal  outfit  for  operating  by  steam 
is  shown  in  Fig.  76,  where  the  engine 
is  directly  connected  to  a  Heald  &  Sisco 
pump.  All  the  trouble  and  vexation 


FIG.    74. — PULSOMETER   STEAM   PUMP. 

from  the  use  of  a  belt  being  done  away 
with,  and  no  loss  of  power  through  slip- 
ping of  belts.  The  machine  can  be 
placed  on  the  barge  which  carries  the 
boiler,  the  suction  pipe  being  run  hori- 
zontally across  as  in  Fig.  56,  while  a 
short  discharge  pipe  discharges  directly 
into  the  river.  Where  electric  power 
plants  are  available  a  still  better  arrange- 
ment will  be  to  have  an  electric  motor 
directly  connected  to  the  pump,  and  all 
the  trouble  incident  to  the  use  of  a  boiler 
on  the  work  will  be  avoided. 


K 


FIG.  75. — SECTION    OF   PULSOMETER. 


98 


fHE  COFFER-DAM  PROCESS  FOR  PIERS. 


Electric  power  can  also  be  used  for  hoisting  and  for  pile  driving. 
Examples  of  the  use  of  motors  on  hoisting  machinery  will  be  given  in  a  later 
article. 

The  suction  should  always  be  fitted  with  a  section  of  smooth-bore  rubber 
hose  (Fig.  77A)  to  give  it  flexibility,  a  length  of  about  eight  feet  being 
usually  sufficient.  The  best  hose  is  made  with  a  spiral  metal  core  which 
adds  to  its  strength  and  durability. 

The  suction  pipe  is  ordinarily  made  of  sections  of  wrought  iron  pipe, 


FIG.  76. — CENTRIFUGAL  PUMP,   DIRECTLY  CONNECTED  TO  ENGINE. 

with  screw  connections,  but  as  this  is  troublesome  to  change  sections,  it  will 
be  found  advantageous  to  use  the  spiral  riveted  pipe  with  flange  couplings 
(Fig.  77B),  and  to  have  extra  sections  from  two  to  six  feet  long,  with  several 
sections  of  each  shorter  length,  so  the  length  of  the  suction  pipe  can  be 
readily  changed  to  suit  the  depth  of  the  excavation.  The  flanges  must  be 
provided  with  rubber  gaskets  to  keep  the  pipe  air  tight. 

The  strainer  (Fig.  77C)  is  used  to  prevent  large  stones,  sticks  or  obstruc- 
tions from  entering  and  clogging  ordinary  pumps,  and  usually  comprises  a 
foot  valve  to  retain  a  pipe  full  of  water  and  make  the  priming  easy.  The 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


99 


strainer  or  end  of  the  suction  pipe  is  usually  placed  in  the  lowest  point,  and 
sometimes  a  box  or  sump  is  provided,  as  a  well  into  which  the  water  is 
drained  from  the  other  and  higher  portions  of  the  work.  A  small  set  of 
falls  should  be  attached  to  the  foot  to  raise  the  pipe  and  clean  out  the  strainer 
when  necessary. 

The  centrifugal  pump  itself  must  be  in  first-class  repair  to  do  economical 
work,  and  should  be  a  large  enough  size  so  that  it  need  not  be  run  beyond 
its  economical  capacity.  The  style  of  pump  to  use  will  depend  upon  the 
work  to  be  done,  but  for  coffer-dam  work  a  vertical  pump  could  not  be  used 
easily  and  need  not  be  considered.  Where  practically  clean  water  is  to  be 
pumped  an  ordinary  style  of  pump  should  be  used,  but  where  much  mud  or 
sand  will  be  drawn  up  a  sand  pump  is  best ;  and  where  a  large  part  of  the 
excavation  is  to  be  done  with  the  pump,  as  at  Topeka,  a  dredging  pump 
will  be  the  proper  type. 


FIG.   77. — SUCTION  DETAIL  FOR   PUMP. 

The  pumping  required  on  the  Chattanooga  work,  5,000  gallons  per  min- 
ute to  a  height  of  about  fifteen  feet,  would  have  been  done  most  econom- 
ically by  a  15-inch  pump,  with  a  40-horse  power  engine  and  a  50-horse 
power  boiler.  But  a  pump  of  this  size  would  not  find  ready  use  in  a  con- 
tractor's work,  and  for  this  reason  two  8-inch  pumps  would  have  been  the 
better  outfit  to  purchase,  unless  the  work  was  very  extensive ;  and  each 
pump  should  be  provided  with  a  25  or  30-horse  power  engine,  so  as  to  run 
the  pumps  somewhat  beyond  the  economical  capacity,  which  could  readily 
be  done  with  a  direct  connected  engine,  where  there  would  be  no  belt  to  slip. 

The  work  required  on  the  Forth  bridge  coffer-dams  could  also  be  done 
by  the  15-inch  pump  above  described,  the  lift  being  about  3  feet  at  the  start 


IOO 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


FIG.  78. — CENTRIFUGAL    PUMP,  DOUBLE  SUCTION. 


and  reaching  18    feet  as  the  dam  was  cleared,  the  340,000  gallons  being 

pumped  out  in  about  one  hour. 

Centrifugal  pumps  are  rarely  required  for  a  lift  of  over  20  feet  on  this 

class  of  work,  which  is  only  slightly  beyond  the  economical  lift,  and  the 

height  should  never  exceed 
30  feet,  which  would  require 
for  the  15-inch  pump  an  en- 
gine of  75-horse  power. 

The  pump  may  be  located 
on  the  coffer-dam,  but  in  case 
of  high  water  during  the  pro- 
gress of  the  work  the  outfit 
may  be  damaged  and  it  is  best 
to  place  the  pump  on  a  boat, 
as  in  Fig.  56,  with  a  section  of 
horizontal  suction  pipe  across 

to  the  work,  which  should  be  as  short  as  possible. 

The  ordinary  type  of  pump  (Fig.  76)  may  be  fitted  with  a  primer,  con- 
sisting of  a  small  hand  force  pump  attached  to  one  side  of  the  pump,  for 

filling     the     pump 

and   suction     pipe. 

A  more  simple  way 

is  to  provide  a  bar- 
rel above  the  pump, 

which  can  be   kept 

full     by     using     a 

small  steam  jet, and 

by  means  of  a  pipe 

with     valve     from 

the   bottom   of  the 

barrel  to  the  top  of 

pump,  the  contents 

can  be  emptied  into 

the  pump  to  prime 

it.      Priming    may 

also  be  easily  ac- 
complished by  in- 
serting a  hose  into 

the   discharge  pipe 

and  filling  the  pump  directly  with  a  steam  jet. 

Double  suction  pumps  (Fig.  78)  allow  the  water  to  enter  on  each  side  of 

the  piston,  and  thus  a  perfect  balance  is  secured,  which  does  away  with  all 


FIG.    79. — DREDGING    PUMP. 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


IOI 


end  thrust  on  the  bearings.  This  pump  is  most  easily  primed  by  using  an 
ejector,  or  a  flap  valve  such  as  is  shown  on  the  discharge  pipe  of  the  dredg- 
ing pump  (Fig.  79)  and  which  serves  to 
retain  the  water  in  the  pump.  Where  a  long 
discharge  pipe  is  to  be  used,  a  quick  closing 
gate  valve  may  be  introduced  into  the  pipe 
near  the  pump. 

Where  the  material  to  be  dredged  out  at 
the  foundation  site  is  mud  or  sand  or  partly 
gravel,  it  can  be  removed  during  the  process 
of  pumping  by  using  a  dredging  pump.  In 
case  there  were  700  yards  of  material  to  be 
removed  and  an  8-inch  pump  was  provided, 
it  would  not  be  advisable  to  count  on  more 
than  10  per  cent,  of  solid  matter  being  dis- 
charged by  the  pump,  as  the  suction  could  not 
be  kept  working  close  up  to  the  sand  or  mud. 
By  using  a  30-horse  power  engine,  a  discharge 
of  2,000  gallons  per  minute  would  be  reached, 
or  with  10  per  cent  of  loose  solid  matter,  the 
excavation  would  be  made  in  less  than  two 
working  days. 

The  piston  of  a  dredging  pump  (Fig.  80) 
is  provided  with  large  openings  to  receive  the  material,  and  the  one  illus- 
trated is  provided  with  side  plates  so  that  all  wear  is  taken  off  the  pump 
casing. 

One  of  the  most  remarkable  pieces  of  work  done  with  this  class  of  pumps 
was  the  use  of  Edwards'  Cataract  pumps  in  dredging  the  ship  channel  in  New 
York  harbor.  This  is  described  in  the  Trans.  Am.  Soc.  C.  E.,  Vol.  25. 
The  work  was  done  by  three  dredges,  which  were  much  the  same  as  small 
sea-going  vessels,  the  largest  being  the  Reliance,  157  feet  long,  and  carrying 
650  cubic  yards  of  dredged  material.  Two  separate  pumps  were  provided, 
each  with  18-inch  suction  pipes,  reaching  from  the  sides  of  the  vessel  and 
parallel  to  it  down  to  the  bottom  to  be  dredged,  being  supported  by  suitable 
hoisting  tackle.  These  boats  were  kept  under  headway  toward  the  dump- 
ing ground  while  the  dredging  was  in  progress.  The  average  load  during 
about  a  month's  working  of  the  Reliance  was  585  cubic  yards  and  the  aver- 
age time  of  loading  about  48  minutes,  while  the  average  number  of  loads 
per  day  was  6.73. 

These  dredges  removed  the  enormous  quantity  of  4,299,858  cubic  yards 
of  material  at  an  average  price  of  24.48  cents  per  yard,  the  lowest  price  being 
about  17  cents,  the  average  price  paid  for  other  forms  of  dredging  being 


FIG.  80. — DREDGING    PUMP 
PISTON. 


102 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


40.53  cents.  On  foundation  work  the  amounts  to  be  removed  would  be 
small  and  the  cost  for  this  reason  much  higher,  yet  owing  to  the  smaller 
cost  of  the  plant  that  would  be  required,  the  cost  need  not  be  greatly  in 
excess  of  the  above.  It  is  usual,  however,  as  the  amount  to  be  dredged  will 
cost  such  a  small  proportion  of  the  total  cost  of  the  substructure,  to  figure 
from  $1  to  $2  per  yard  for  excavation  in  ordinary  coffer-dams. 

Reference  has  already  been  made  to  hand  dredging  and  a  very  cheap  and 
effective  scraper  was  illustrated  in  Fig.  8.  Where  dredging  is  to  be  done  in 
tubes,  wells  or  puddle  chambers,  it  can  be  done  by  a  clam-shell  dredge  or 
grapple  such  as  was  shown  in  Fig.  57,  in  use  on  the  Hawkesbury  founda- 
tions. 

The  Lancaster  dredge  (Fig.  81)  is  a  well  known  form  of  this  type  of 


FIG.  81. — LANCASTER   GRAPPLE. 

machine,  and  can  be  operated  from  an  ordinary  derrick  which  is  served  by 
a  double-drum  hoisting  engine.  This  dredge  will  work  best  of  course  where 
there  is  some  depth  of  soft  material  to  be  removed.  While  a  large  dredge 
would  generally  be  hired  by  a  contractor,  these  buckets  can  be  owned  by 
him  and  the  work  carried  on  cheaply  and  conveniently. 

Sand  diggers  such  as  were  mentioned  in  Article  II  can  often  be  hired 
where  other  means  are  not  at  hand,  or  they  can  be  rigged  up  very  cheaply 
if  necessary.  A  very  simple  one  (Fig.  82)  can  be  built  on  an  ordinary 
barge,  the  engine  being  an  ordinary  one  with  a  vertical  boiler,  while  the 
buckets  are  mounted  in  a  very  simple  manner  and  operated  through  a  well 
in  the  center  of  the  boat.  Such  a  dredge  will  dig  about  100  yards  of  sand 


THE    COFFER-DAM  PROCESS  FOR  PIERS. 


103 


per  day,  with  only  two  men  to  attend  it,  and  will  use  less  than  one-half  ton 
of  cheap  coal,  the  total  cost  per  yard  thus  running  below  five  cents.  Large 
elevator  dredges  of  this  type  are  very  elaborate  affairs,  and  as  they  are  in 
wide  use  they  can  often  be  hired  for  making  excavations. 

The  best  known  form  of  dredge,  perhaps,  is  the  dipper  dredge.  The 
Osgood  machines  (Figs.  83  and  84)  in  use  on  the  New  York  State  canals  are 
among  the  best  machines  of  this  kind  in  use.  Such  dredges  are  more  simple 
in  construction  than  elevator  machines,  and  are  consequently  easier  and 

cheaper  to  keep  in 
repair.  The  hull 
is  70  x  17  x  6  feet 
with  two  6 -feet  pon- 
toons which  are  re- 
moved when  going 
through  locks. 
The  engines  consist 
of  a  double  drum 
main  engine  with 
8x10  inch  cylin- 
ders, a  swinging 
engine  with  6x8 
inch  cylinders,  and 
a  crowding  engine, 
5x6  inch  cylinders, 
which  are  all  used 
in  operating  the 
digger  of  1^  yards 
capacity  on  a  steel 
boom  45  feet  in 
length. 

The     crowding 
engine   is   used  to 

control  the  dipper  and  enables  it  to  make  a  practically  level  bottom  at  one 
cut,  and  also  thrusts  the  dipper  far  enough  beyond  the  boom  to  allow  it  to 
dump  fifty-two  feet  from  the  center.  This  dredge,  which  cost  complete 
$10,000,  is  operated  by  a  crew  of  only  four  men  and  consumes  but  one  ton 
of  coal  per  day  of  twelve  hours,  the  average  excavation  during  four  months' 
work  being  549  cubic  yards  per  day.  The  machine  has  sufficient  power  to 
dig  hardpan,  boulders,  and  very  soft  shale  rock. 

A  dredge  of  this  make,  of  3^1  yards  capacity,  working  in  mud  and  sand, 
has  dug  material  at  the  very  low  actual  cost  of  .99  of  one  cent  !  This  of 
course  was  an  exceptional  case,  and  the  cost  will  rarely  fall  below  five 


FIG.  82. — SAKD  DIGGER. 


THE   COFFER-DAM  PROCESS   FOR   PIERS. 


105 


cents  per  yard  on  easy  work  at  a  depth  not  exceeding  ten  feet,  and  in  such 
small  amounts  as  would  have  to  be  dredged  on  coffer-dam  work  and  in 
about  twenty  feet  of  water  the  actual  cost  would  likely  reach  fifteen  cents 
per  yard.  In  case  the  dredge  should  be  hired  to  do  the  work,  a  charge 
of  from  twenty  to  thirty  cents  per  yard  would  not  be  excessive  depending 
of  course  on  the  class  of  material  and  the  amount. 


ARTICLE    IX. 

THE    COFFER-DAM    PROCESS    FOR    PIERS. 

THE    FOUNDATION. 

HE  coffer-dam  is  only  the  means  of  reaching  a  desired  end,  and  this  must 
be  borne  in  mind  and  the  construction  made  as  simply  as  possible  to 
obtain  a  first-class  foundation. 

When  the  coffer-dam  is  completed  and  pumped  out  work  can  then 
proceed  if  the  pumps  are  able  to  control  the  water  easily.  The  charac- 
ter of  the  foundation  having  been  previously  decided  upon,  after  a  careful 
examination  of  the  site,  it  is  assumed  that  the  temporary  work  has  been 
executed  in  a  manner  which  is  properly  related  to  the  permanent  structure. 

The  different  kinds  of  bottom  likely  to  be  encountered  are  :  First,  light 
sand  and  gravel  or  mud  of  unknown  depth;  second,  similar  material  over- 
lying either  cemented  gravel,  clay,  hardpan  or  rock;  third,  a  clean  rock 
bottom,  which  is  approximately  smooth  and  level;  fourth,  a  sloping  rock 
bottom,  which  is  either  smooth  or  rough,  and  fifth,  a  rough  and  irregular 
rock  bottom. 

Should  the  bottom  be  of  the  first  kind — light  sand  and  gravel  or  mud  of 
unknown  depth — the  soft  upper  layer  may  have  been  removed  by  a  dredge 
previous  to  the  building  of  the  dam,  or  it  may  be  removed  by  a  dredge  or 
grapple  from  within  the  inclosed  area,  and  without  the  necessity  of  keeping 
the  dam  pumped  out,  or  pumping  may  be  kept  up  with  a  dredging  pump 
and  the  light  material  removed  in  this  way,  after  which  the  heavier  material 
may  be  removed  as  deep  as  necessary  by  hand  shoveling  and  a  dirt  box,  as 
shown  in  Fig.  56.  In  such  a  bottom  the  foundation  is  usually  made  by 
driving  piles  from  two  to  four  feet  centers,  this  distance  being  regulated  by 
the  bearingpower,  as  determined  from  Wellington's  formula  in  Article  IV, 
and  building  upon  the  tops  of  the  piles,  after  they  have  been  cut  off  to  a  level 
below  low  water,  a  grillage  of  timber.  The  space  between  the  piles  should 
be  filled  with  broken  stone  or  concrete,  and  the  grillage  placed  entirely  below 
low  water,  the  coffer-dam  being  kept  pumped  out  to  allow  this  work  to  be 
done,  and  also  during  the  laying  of  the  footing  courses  of  the  masonry 
which  are  below  the  water. 

When  the  soft  bottom  overlays  good  clay,  hardpan  or  rock,  as  in  the 
second  case,  and  the  depth  exceeds  20  or  25  feet  below  the  water  surface, 
piles  may  be  driven  to  the  harder  substratum  and  act  as  bearing  piles.  But 
when  the  depth  is  in  the  region  of  20  feet  or  less,  it  is  best  to  excavate  and 

1 06 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


ID/ 


place  the  foundation  masonry  directly  upon  the  solid  bottom.  The  founda- 
tion will  be  of  the  character  described  for  some  of  the  following  cases: 

The  third  class  is  similar  to  the  foundation  at  Chattanooga  after  the 
gravel  was  removed.  The  fissures  in  the  rock  are 
filled  up  or  closed  with  cement  and  concrete,  and  a 
leveling  course  of  concrete  put  down  on  which  to  found 
the  pier.  (Fig.  49). 

Bottoms  of  the  fourth  class  should  have  all  the 
loose  and  decomposed  rock  removed  and  steps  cut  out 
by  blasting  and  wedging,  to  give  a  secure  hold  for  the 
foundation,  but  if  it  is  simply  rough  and  irregular  a 
leveling  course  of  concrete  will  be  all  that  is  required 
on  which  to  start  the  pier.  Bottoms  of  clay  and  hard- 
pan  will  require  a  very  similar  treatment,  except  that 
the  leveling  course  of  concrete  must  be  made  of  suffi- 
cient thickness  to  properly  distribute  the  pressure, 
which  will  seldom  be  less  than  three  feet  and  can  often 
be  increased  with  advantage  to  six  or  eight  feet.  An 
example  of  the  stepping  of  rock  bottom  was  given  in 
the  account  of  the  Forth  Bridge  piers  in  Article  VII 
and  was  shown  by  the  dotted  lines  in  Fig.  64. 

Where  there  is  a  current  caused  by  leakage  through 
the  sides  of  a  coffer-dam,  or  from  the  bottom,  or  if  the 
water  within  the  dam  is  agitated  by  the  pumping,  it 
will  be  best,  after  the  bottom  is  clean  and  properly 
prepared,  to  allow  the  water  to  run  in  and  then  de- 
posit the  concrete  through  the  still  water.  This  has 
been  successfully  accomplished  through  25  or  30  feet 
of  water,  and  while  some  engineers  recommend  allow- 
ing the  concrete  to  set  from  one  to  three  hours  before 
depositing,  to  prevent  the  cement  from  washing  out  of 
the  concrete,  this  is  not  necessary  nor  advisable  if  the 
proper  care  is  exercised  and  the  prcfper  apparatus  used. 
The  concrete  should  be  made  from  one-third  to  one- 
half  richer  than  would  be  used  for  similar  open  air 
work,  as  there  will  be  some  loss  of  strength. 

The  simplest  method  is  to  deposit  the  concrete  in 
paper  sacks  by  sliding  them  down  a  smooth  wooden 
or  iron  chute,  or  by  loading  them  into  a  box  or  skip 

and  dumping  them  out  after  the  box  reaches  the  bottom.  The  sacks 
should  be  of  tough  paper,  similar  to  flour  sacks,  and  when  they  reach  the 
bottom  they  may  be  broken  by  a  pike  pole  and  the  concrete  allowed  to  run 


FIG.  85.— METAL  TUBE 
FOR  CONCRETING. 


io8 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


together.     Thin  cloth  sacks  are  sometimes  used  and  they  become  fairly  well 
cemented  together  by  the  mortar  which  oozes  through. 


IT 

o 

o 

fo 

o  :    . 

o 

. 

0 

0 

o  : 

o 

o 

o 

o  I: 

0 

o 

0 

o  i 

0 

Q 

o 

-J  I— 

==3^-r= 

FIG.  86. — METAI,  BUCKET  FOR  CONCRETING. 

Where  the  amount  of  concrete  is  considerable  it  will  be  best  to  use  a  tube 
or  bottom  dumping  box.     For  placing  concrete  under  water  on  the  Bouci- 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


109 


caii  It  bridge  over  the  river  Saone  in  France  a  wooden  tube  16  inches  square 
was  used.  This  is  described  in  the  Engineering  News  of  May  18,  1893. 
The  tube  was  carried  transversely  across  the  caisson  on  a  traveling  crane 
which  ran  lengthwise  of  the  caisson  on  tracks  on  the  sides,  thus  allowing 
the  tube  to  be  moved  in  any  desired  direction.  The  tube  was  built  in  sec- 
tions which  could  be  easily  removed,  was  provided  with  a  hopper  at  the  top 
into  which  the  concrete  was  dumped,  and  a  drop  door  at  the  bottom  to  Jet 


—   PL;  AN   — 

FIG.  87.— CONCRETE  PIERS.    RED  RIVER  BRIDGE. 

out  the  concrete.  The  tube  was  filled  as  it  was  lowered  down  into  the 
water,  and  opened  when  within  16  inches  of  the  bottom.  As  concrete  was 
dumped  in  above,  the  tube  was  moved  about  and  a  16- inch  layer  of  concrete 
deposited.  When  one  layer  was  complete,  another  of  the  same  thickness  was 
deposited.  This  method  of  using  16-inch  layers  was  said  to  have  obviated 
laitance  or  the  exuding  of  the  gelatinous  fluid  which  prevents  uniform 


I  IO 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


setting.  The  concrete  was  deposited  about  the  heads  of  the  piles  and  no 
grillage  used.  The  thickness  of  the  concrete,  which  was  deposited  at  the 
rate  of  from  90  to  100  yards  per  day,  was  9.84  feet,  and  was  allowed  to  set 
fourteen  days  before  the  pier  was  begun. 

A  metal  tube  may  be  used,  such  as  was  employed  on  the  Harvard  bridge 
at  Boston  by  W.  H.  Ward.  This  tube  (Fig.  85)  was  not  provided  with  a 
bottom  and  the  first  filling  of  the  tube  was  consequently  done  after  the  tube 
was  lowered  and  the  concrete  became  somewhat  washed.  This  may  easily 

be  prevented  by  using  con- 
crete in  paper  sacks  to  fill 
the  tube  the  first  time. 
The  tube  was  suspended 
from  a  derrick  and  was 
moved  about  so  as  to  keep 
the  concrete  level  and  de- 
posit it  in  layers.  This  ac- 
count is  taken  from  Vol. 
31  of  the  Engineering 
News,  from  which  is  taken 
the  following  description 
of  a  metal  bucket  used  by 
W.  D.  Taylor  on  the  Coosa 
river. 

This  bucket  (Fig.  86) 
was  of  riveted  construc- 
tion and  held  one  yard  of 
concrete.  The  maximum 
depth  of  water  was  26  feet, 
at  which  depth  the  bucket 
and  its  load  became  so 
lightened  that  the  bucket 
tripped  as  soon  as  the 
flanges  touched  the  bot- 
tom. Similar  boxes  are 
often  constructed  of  wood, 

or  they  are  often  made  "V"-shaped,  one  side  being  arranged  to  open  and 
dump  the  load. 

For  concrete  work  of  this  character  natural  cement  is  often  used,  but  on 
all  important  work  Portland  cement  should  be  employed.  The  proportions 
range  from  1  of  cement,  2  of  sand  and  4  of  broken  stone,  to  1  of  cement,  3  of 
sand  and  6  of  broken  stone. 

On  such  a  base  either  a  masonry  or  monolithic  concrete  pier  may  be 


FIG.   88. — CONCRETE    FORMS.      RED   RIVER  BRIDGE. 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


Ill 


constructed.  The  pier  at  Little  Rock  (Fig.  52)  was  of  this  construction  and 
of  the  composition  given  in  Article  VI.  A  similar  piece  of  work  was  con- 
structed on  the  Red  River  bridge  on  the  St.  Louis  &  San  Francisco  Railway 
and  is  described  in  the  Engineering  News  of  June  2,  1888,  by  C.  D.  Purdon, 
assistant  engineer  in  charge  of  the  work,  under  James  Dun,  Chief  Engineer, 
The  cribs  were  filled  with  Louisville  cement  concrete  up  to  within  two  feet 
of  low  water,  on  which  was  built  the  pier.  (Figs.  87  and  88.) 

''After the  crib  had  been  filled  with  concrete  and  the  surface  leveled  off, 
the  center  lines  of  the  pier  were  located  and  a  frame  of  2"x8"  plank  the 
shape  of  the  pier,  and  four  inches  larger  to  allow  for  lagging,  was  placed  in 
exact  position  and  held  by  pieces  spiked  to  the  crib.  On  this  frame  upright 
posts  6"x6"  and  5'  10"  high,  with  a  batter  of  one-half  inch  per  three  feet 
were  set  in  the  position  shown  on  the  drawing,  then  the  feet  spiked  to  the 
frame  and  another  frame  similar  to  the  first,  but  six  inches  narrower  placed 
on  them.  This  again  was  brought  to  exact  position  and  braced  to  the  crib 


G«./23 


FIG.  89. — CONCRETE  FORMS.      ILLINOIS  AND  MICHIGAN  CANAI,. 

and  the  frame  completed  by  putting  lagging  of  2-inch  plank  inside  the  posts 
and  spiking  to  them.  This  lagging  was  horizontal  in  the  body  of  the  pier 
and  vertical  (2"x4")  at  the  ends,  beveled  pieces  being  introduced  in  the 
ends  at  intervals  to  make  up  the  difference  of  the  upper  and  lower  circles. 
Next  2"x6"  planks  were  placed  across  on  the  top  of  the  posts,  running  clear 
through  the  pier,  to  act  as  braces.  In  the  rest  of  the  frames  these  braces 
were  allowed  to  extend  about  six  feet  on  each  side  and  the  frame  braced  by 
spiking  plank  to  them  and  to  the  vertical  posts.  After  a  section  of  frames 
was  completed  a  bed  of  cement  mortar  about  two  inches  thick  was  spread  all 
over  the  concrete  in  the  crib.  On  this  the  rough  stone,  in  such  pieces  as  one 
man  could  easily  handle,  was  placed  so  that  no  two  pieces  would  be  closer 
than  two  inches,  nor  any  piece  within  two  inches  of  the  frame,  the  stone 
being  thoroughly  wet  before  laying. 

"Next,  on  this  course  of  stone  another  bed  of  mortar  was  placed,  sufficient 
to  fill  all  the  spaces  between  the  stones  and  remain  about  two  inches  thick 
above  them.  It  was  then  well  rammed  with  rammers  made  by  inserting  a 


112 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


handle  in  a  section  of  a  pile,  except  at  the  edges,  where  a  rammer  made  of  a 
2-inch  plank  cut  in  the  shape  of  a  spade  was  used,  to  insure  a  perfect  skin 
of  cement  without  any  breaks.  After  this  had  been  well  rammed,  another 
layer  of  stone  was  placed  and  covered  with  mortar  as  before,  and  so  on. 

"The  coping,  which  was  made  similar  to  the  body  of  the  pier,  was  fin- 
ished by  about  \Yz  inches  of  cement  mixed  with  sand  one  to  one,  fluid 

CRUSHING  PLANT  AND  SIJVS. 


n 


Side  Elevation, 


Elevalion  t>f 
Rear  Bent  and  Platform* 


Front  Elevalion 


CONCRETE    MIXING  PLANT. 


Side  -Elevation 
FIG.  90. — STONE   CRUSHER   AND   CONCRETE   MIXER.       IIJvINOIS   AND    MICHIGAN    CANAI, 

enough  to  be  struck  off  by  a  straight  edge,  the  top  of  the  frame  being 
dressed  and  leveled  for  that  purpose. 

" After  the  pier  had  been  completed  the  frames  were  removed  and  the 
braces  running  through  the  piers  cut  off  by  a  chisel  inside  the  concrete. 
Then,  to  make  a  smooth  surface,  the  pier  was  thoroughly  wet  and  plastered 
with  a  mixture  of  one  part  sand  to  one  part  cement,  after  all  the  rough  or 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


loose  portions  had  been  scraped  off.     This  was  mainly  done  for  appearance," 
The  mortar  for  the  body  of  the  pier  was  made  of  one  part  Alsen's  Ger- 
man Portland  cement  and  four  parts  of  sand.     There  was  used  about  l^i 
barrels  of  cement  to  a  cubic  yard  of  completed  pier.     In  mixing  the  mortar 

eleven  ordinary  pails 
full  of  water  were  used 
to  one  barrel  of  ce- 
ment, which  caused 
the  water  to  just  ap- 
pear on  the  surface 
when  the  tamping  was 
done. 

The  lock  walls  on 
the  Illinois  and  Mis- 
sissippi canal  have 
been  constructed  of 
monolithic  concrete 
under  Captain  W.  L. 
Marshall,  Corps  of  En- 
gineers. The  work 
was  executed  under 
L.  L.  Wheeler,  en- 
gineer in  charge,  from 
whose  account  in  the 
report  of  the  Chief  of 
Engineers  for  1894, 
the  followingis  taken: 
"The  rules  adopt- 
ed for  the  work  were 
adhered  to  and  are 
worthy  of  careful 
study. 

"I.  The  forms  or 
molds  of  the  walls  will 
be  divided  by  vertical 


FIG.  91. — AMERICAN  HOIST  AND  DERRICK  CO. 
GUY  DERRICK. 


DOUBLE  DRUM 


partitions  perpendicu- 
lar to  the  longest  axis 
of  the  mass,  and  the  walls  be  constructed  by  filling  alternate  sections. 

"II.  The  sections  will  be  filled  in  horizontal  layers,  well  rammed,  each 
layer  to  be  deposited  before  the  'initial  set'  of  the  previously  deposited  layer. 
When  the  work  of  filling  a  section  is  begun  it  must  proceed  without  inter- 
mission to  completion,  working  night  and  day  if  necessary. 


114 


THE  LOFFER-DAM  PROCESS  FOR  PIERS. 


"III.  The  facing  and  backing  must  go  on  simultaneously  in  the  same 
horizontal  layers,  using  the  same  cement  in  the  facing  as  in  the  backing,  with 
no  defined  lines  of  demarcation  between  the  facing  which  contains  no  stone 
and  the  concrete  backing. 

"IV.  When  the  top  surface  of  the  coping  is  reached  it  will  be  finished 
after  ramming  by  cutting  off  the  excess  by  a  straight  edge,  and  rubbed 

smooth  and  hard  by  a  float. 
No  plastering  or  wet  finishing 
coat  will  be  allowed. 

"V.  The  facing  of  the 
walls  will  not  be  finished  by 
plastering  or  washing  with 
cement  after  the  forms  are  re- 
moved, nor  dressed  in  any 
manner  beyond  chiseling  away 
rough  ridges  should  the  plank 
forming  not  be  smooth. 
FIG.  92. — SINGLE  DRUM  HORSEPOWER.  CON-  "VI.  The  concrete  shall 

TRCATORS  PI<ANT   MFG.  CO.  V 


will  take,  without  water  showing  after  ramming,  or  without  'quaking'  upon 
ramming. 

"VII.  At  such  intervals  as  may  be  necessary  vertical  wells,  at  least  one 
foot  square  will  be  formed  along  the  mid- 
dle of  the  masses  of  concrete,  reaching  to 
near  the  bottom  thereof.  The  masses  of 
concrete  after  forming  will  be  kept  shel- 
tered from  the  sun,  the  outer  surfaces 
kept  moist  and  the  wells  kept  filled  with 
water  until  well  set,  or  about  three  weeks. 
The  walls  will  then  be  filled  with  con- 
crete. 

"VIII.  In  preparing  the  cement  for 
mixing  with  other  ingredients  of  con- 
crete, from  five  to  ten  barrels  will  be.  kept 
thoroughly  mixed  dry,  to  guard  against 
chance  barrels  of  defective  cement,  and  FIG.  93._DouBLE  DRUM  HOIST  ENGINE. 
the  necessary  quantity  of  cement  will  be  UDGERWOOD  MFG.  co. 

taken  for  each  batch  from  this  mixture. 

"IX.  Two  cements  of  different  qualities  shall  not  be  used  in  the  same 
section,  but  as  far  as  practicable  each  mass  shall  be  homogeneous  throughout, 
but  a  slight  excess  of  cement  in  the  facing  to  reduce  its  capacity  to  absorb 
water." 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  1 1  5 

The  rate  at  which  the  concrete  was  deposited  in  the  work  was  determined 
by  the  rate  of  ramming,  and  but  one  yard  every  five  minutes  was  deposited. 
The  forms  (Fig.  89)  were  lined  with  dressed  pine  plank  4  by  8  inches  on  the 
face,  of  uniform  thickness,  and  with  2-inch  rough  plank  on  the  back. 

Rough  plank  is  sometimes  used  on  such  work  and  lined  with  oiled  paper, 
or  ordinary  dressed  plank  may  be  used  and  coated  with  soft  soap.  In  most 
sections  of  the  country  crushed  broken  stone  can  be  obtained,  but  owing  to 
the  magnitude  of  this  work  a  crusher  was  built  (Fig.  90)  and  was  found  to 
work  very  satisfactorily.  The  concrete  mixer  shown  in  Fig.  90  was  oper- 
ated by  a  15-horse  power  portable  engine.  The  proportions  finally  adopted 
for  the  concrete  were  one  of  cement,  three  and  one-third  of  gravel,  and  four 


FIG.    94. — LIDGERWOOD    ELECTRIC    HOIST. 


of  broken  stone,  while  the  facing  and  coping  were  composed  of  one  part 
cement  and  two  parts  of  clean  river  sand. 

That  the  sand  for  concrete  be  clean  and  sharp  is  very  essential,  and  any 
loam  or  dirt  must  be  washed  out.  Equally  essential  is  good,  clean,  sharp, 
broken  stone  without  dust  or  dirt.  The  cement  used  on  the  above  work  was 
a  German  Portland,  but  several  of  the  American  Portlands  are  first-class  and 
will  give  as  good  results  as  the  imported. 

Where  good,  fresh  cement  is  being  supplied,  a  few  tests  to  a  carload  will 
be  sufficient,  and  for  cements  of  the  grade  of  Atlas  or  Empire,  the  guarantee 
of  the  manufacturer,  supplemented  by  a  few  tests,  should  be  sufficient,  But 


1 1 6  THE  COFFER-DAM  PROCESS  FOR  PIERS. 

for  cements  which  have  been  shipped  by  water  tests  should  be  made  from 
every  five  or  ten  barrels. 

The  Atlas  Cement  Company  recommend,  for  concrete  laid  in  open  air 
on  moist  ground  where  great  weight  must  be  carried,  one  of  cement,  two  of 
clean  sharp  sand,  and  lour  of  2-inch  broken  stone;  this  sand  and  cement  to 
be  thoroughly  mixed  dry,  then  just  enough  water  added  to  thoroughly 
moisten,  and  the  mass  turned  over  at  least  twice,  when  the  stone  is  to  be 


FIG.    95.— UDGERWOOD    CABI/EWAY    CARRIAGE    AND    SKIP. 

added  in  a  thoroughly  wet  condition.  This  must  then  be  put  at  once  into  the 
molds  and  well  rammed. 

Where  a  solid  bottom  is  to  be  built  upon,  the  proportions  of  one  of 
cement,  three  of  sand  and  six  of  broken  stone  are  recommended.  For 
ordinary  construction  one  of  cement,  four  of  sand  and  eight  of  broken 
stone,  while  to  obtain  a  concrete  as  strong  as  ordinary  natural  cement  con- 
crete, one  of  cement,  five  of  sand  and  ten  of  broken  stone  can  be  used. 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  1 1/ 

The  average  cost  of  such  concretes,  including  labor,  tools,  timber  forms 
and  a  fair  profit  to  the  contractor  would  be  for  the  first  $8  per  yard,  for  the 
second  $7,  for  the  third  $6,  and  for  the  fourth  $5. 

Where  the  leveling  course  of  concrete  has  been  put  in  and  the  pier  is  to 
be  of  stone,  the  footing  course  should  be  of  carefully  selected  material. 
They  should  be  large  stones  with  good  beds,  and  should  be  as  thick  or  pref- 
erably thicker  than  the  courses  above.  Where  the  bearing  pressure  does 
not  exceed  two  tons  per  square  foot,  the  footing  courses  may  be  stepped  by 
allowing  each  course  to  project  about  one  and  one-third  times  its  thickness, 
depending  of  course  on  the  quality  of  the  stone. 

The  usual  way  of  handling  the  material  for  foundations  and  piers,  is  to 
boat  it  to  the  site,  where  it  is  placed  by  a  stiff- leg  derrick,  or  if  guys  can  be 
used,  by  a  derrick  with  wire  rope  guys.  The  fittings  for  such  derricks  can 
be  obtained  from  a  number  of  firms,  an  American  Hoist  and  Derrick  Company 
outfit  being  shown  in  Fig.  91.  This  is  rigged  to  be  operated  by  a  double  drum 
hoist,  which  can  be  one  operated  by  horse  power  (Fig.  92)  if  the  piers  are 
near  the  bank  and  if  steam  power  is  not  available.  The  usual  form,  how- 
ever, is  a  double  drum  steam  hoist  like  the  Lidgerwood  machine  shown  in 
Fig.  93.  Where  electric  power  is  available  an  electric  hoist  (Fig.  94)  should 
be  used,  as  it  will  be  found  much  more  convenient. 

Works  of  any  magnitude  should,  however,  be  fitted  from  the  beginning 
with  a  cableway,  which  will  avoid  the  necessity  of  boating  the  materials, 
erecting  of  large  derricks,  and  facilitate  in  every  way  the  prosecution  of  the 
work,  besides  often  making  a  balance  on  the  right  side  of  the  ledger.  The 
Lidgerwood  cableway  on  Dam  No.  11  of  the  Great  Kanawah  river,  a  tower 
of  which  can  be  seen  in  Fig.  9,  had  a  span  of  1,505.5  feet  and  carried  a  net 
load  of  four  tons  on  a  main  cable  2%  inches  in  diameter.  The  stone  quarry 
was  located  on  one  bank  and  the  stone  was  taken  directly  to  the  stone  yard 
and  to  the  work  in  the  river.  A  seam  of  coal  in  the  quarry  also  supplied 
fuel  for  the  dredges  and  pumps,  the  coal  being  handled  by  the  cableway,  as 
was  also  the  material  from  the  railroad  siding  on  the  opposite  bank. 

The  details  of  these  cableways  have  been  developed  and  perfected  to  a 
wonderful  extent,  as  a  result  of  their  use  on  the  Chicago  Drainage  channel. 
The  engine  for  operating  one  of  these  with  a  capacity  of  eight  tons  has 
double  10x12  cylinders,  the  cranks  being  set  at  an  angle  of  90  degrees  and 
is  provided  with  reversing  link  motion.  The  double  drums  regulate  both 
the  hoist  at  a  speed  of  300  feet  per  minute  and  the  travel  along  the  cable  at 
1,000  feet  per  minute.  A  70-horse  power  boiler  is  required. 

The  carriage  and  skip,  which  are  automatic  in  action,  are  shown  in  Fig. 
95,  the  capacity  of  those  on  the  Drainage  channel  being  1.8  yards,  and  the 
average  of  a  month  being  about  600  yards  per  day  of  ten  hours.  The  cost 
of  operation,  including  labor,  fuel  and  everything  except  interest  on  plant 


US 


THE   COFFER-DAM   PROCESS  FOR  PIERS. 


and  repairs  was  less  than  $18  per  day  or  from  three  to  four  cents  per  yard. 

The  cableway  on  the  Coosa  dam  and  lock   (Fig.  96)  had  a  capaciiy  of 

about  eight  tons  and  made  a  round  trip  on  an  average  of  about  three  minuteSc 


Such  a  plant  is  out  of  reach  of  high  water  and  of  trains  where  used  over  rail- 
road tracks  as  at  the  North  avenue  bridge  in  Baltimore. 

The  Court  street  stone  arch  bridge  at  Rochester,  N.  Y.,  of  eight  spans, 
was  constructed  with  the  aid  of  a  cableway,  which  was  also  used  ro  remove 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  r  ICj 

the  old  bridge  and  piers.  A  cableway  of  one  span  was  used  to  construct 
the  Melan  concrete  arch  bridge  at  Topeka,  Kan.  The  bridge  has  five  spans 
and  a  total  length  of  650  feet.  During  the  extreme  high  water  in  the  early 
part  of  1 897, '  when  everything  was  completely  inundated,  and  an  ordinary 
derrick  plant  would  have  been  swept  away,  the  cableway  was  high  and  dry 
out  of  reach  of  the  flood. 

The  prevailing  low  prices  of  contract  work  make  it  necessary  to  employ 
every  improvement  on  important  engineering  work,  and  the  cableway  has 
doubtless  come  to  stay  as  one  of  the  most  remarkable  of  our  tools. 


ARTICLE   X. 

THE    COFFER-DAM    PROCESS    FOR    PIERS. 

.LOCATION   AND   DESIGN   OF   PIERS. 

IERS  of  a  bridge  cannot  always  be  located  with  reference  to  easy  con- 
struction nor  spaced  at  economical  distances  apart.  In  thickly  settled 
parts  of  a  country,  or  as  part  of  an  existing  line  of  communication, 
the  bridge  must  be  located  usually  in  a  position  previously  determined, 
and  the  piers  can  only  be  spaced  with  regard  to  economy,  provided  due 
regard  can  at  the  same  time  be  paid  to  the  needs  of  navigation,  gov- 
ernment requirements  and  sufficient  waterway. 

Where  the  bridge  is  to  be  constructed  in  a  new  country,  or  upon  a  new 
line  of  road,  the  crossing  should  be  selected  where  the  river  is  of  moderate 
width;  that  is,  not  so  wide  as  to  demand  a  structure  of  excessive  length 
and  probably  of  excessive  cost,  nor  so  narrow  that  the  current  will  be  exceed- 
ingly swift  and  make  the  foundations  very  difficult  and  costly  to  build, 
unless,  of  course,  it  is  narrow  enough  to  admit  of  using  a  one  span  structure 
at  a  reasonable  cost. 

On  all  the  large  navigable  rivers,  the  cnannel  is  fixed  and  the  length  of 
the  channel  span  prescribed  by  law,  as  is  also  the  method  of  procedure  in 
obtaining  the  approval  of  the  government  engineers.  The  Secretary  of  War 
must  be  furnished  with  a  copy  of  the  state  law  authorizing  the  construction 
of  the  bridge,  certified  to  by  the  Secretary  of  State  under  seal;  drawings  in 
triplicate  showing  the  general  plan  of  the  bridge;  a  map  in  triplicate  show- 
ing the  location  of  the  bridge,  giving  for  the  distance  of  one  mile  above  and 
one-half  mile  below  the  proposed  location,  the  high  and  low  water  lines 
upon  the  banks  of  the  stream,  the  direction  and  strength  of  the  current  at 
high  and  low  water,  with  the  soundings  accurately  showing  the  bed  of  the 
stream,  and  the  location  of  any  other  bridge  or  bridges,  such  map  to  be  suf- 
ficiently in  detail  to  enable  the  Secretary  of  War  to  judge  of  the  proper  loca- 
tion of  the  bridge.  In  addition  to  the  above,  if  the  applicant  is  a  corpora- 
tion, there  will  be  required  a  certified  copy  of  their  articles  of  incorpora- 
tion, a  certified  copy  of  the  minutes  of  the  organization  of  the  company, "and 
an  abstract  of  the  minutes  of  the  corporation,  showing  the  present  officers  of 
the  company,  all  duly  certified  to. 

When  the  location  of  the  bridge  has  been  made,  a  thorough  examination 
of  the  site  must  be  instituted.  Soundings  must  be  made  to  determine  the 
depth  of  the  stream  at  low  water;  ordinary  and  extreme  high  water  lines 

120 


THE   COFFER-DAM  PROCESS  FOR  PIERS.  121 

must  be  established  and  the  flow  of  the  stream  be  obtained.  A  careful 
examination  must  be  carried  out  as  to  the  character  of  the  river  bed,  and 
drillings  made  to  learn  the  character  and  thickness  of  strata  and  the  distance 
to  bedrock,  as  well  as  the  quality  of  it. 

Borings  to  a  small  depth  may  be  made  by  hand  drills  (Fig.  97a),  which 
are  operated  by  striking  with  a  sledge  and  turned  constantly  to  keep  a  round 
hole,  or  if  long  and  heavy  they  will  cut  their  way,  if  simply  raised  up  and 


(Fig.  97a) 


(Fig.  97b) 


HAND    DRILL    AND    SWAB. 


allowed  to  drop,  with  their  own  weight.  The  hole  is  kept  partly  filled  with 
water  and  can  be  cleaned  out  with  a  small  sand  pump  or  with  a  swab  (Fig. 
^7b)  made  from  a  stick  slivered  at  the  end,  which  will  also  bring  up  samples. 

The  Pierce  steel  prospecting  augur  is  a  tool,  which  can  also  be  used 
without  a  derrick  to  bore  test  holes  from  10  to  50  feet  into  loose  soils  or  clay. 
Holes  from  2^  to  6  inches  in  diameter  can  be  drilled  and  samples  obtained. 
The  augur  can  be  turned  either  by  hand  wrenches  or  by  horse  power. 

Where  the  borings  are  to  be  of  an  extensive  character  a  well-drilling 
machine  can  be  utilized,  such  as  shown  in  Fig.  98,  and  which  can  be  run 
onto  an  ordinary  flat-boat  and  towed  to  place. 

The  tools  for  drilling  are  a  temper  screw  for  regulating  the  height  of  the 
drill,  a  sinker  bar  to  give  the  weight,  steel  jars  and  drilling  bits.  A  sand 
pump  is  used  to  clean  the  hole  and  obtain  samples;  rope  spears,  rope  knives 
and  fishing  tools  to  remove  lost  rope,  tools  and  pebbles  or  other  obstructions. 
The  drill  holes,  unless  through  rock,  are  cased  with  iron  pipe  which  can  be 
withdrawn  when  the  hole  is  completed. 

The  borings  made  by  the  Mississippi  River  Commission  were  very 
extensive  and  a  special  tripod  apparatus  (Fig.  99)  was  devised  with  a  view 
to  easy  transportation  and  easy  repair  in  the  field.  The  tripod  was  30  feet 
in  height,  with  a  strong  head  or  cap,  surmounted  by  a  galvanized  iron  guide 
pipe  20  feet  in  height,  in  two  sections,  and  held  in  place  with  guy  ropes. 
The  men  operating  the  tools  stood  upon  the  triangular  platforms  which  were 
attached  to  the  legs.  The  casing  was  iron  pipe  in  10-feet  lengths  and 
screwed  together  so  as  to  present  a  smooth  surface,  while  the  bottom  was 


122  THE  COFFER-DAM  PROCESS  FOR  PIERS. 

provided  with  a  steel  cutting  shoe,  having  a  mouth  slightly  larger  than  the 
pipe.  The  sinking  is  accomplished  by  driving  and  by  twisting;  the  driving 
being  done  by  means  of  the  clamp  on  the  pipe  and  the  maul  sliding  on  the 
pipe.  (Fig.  100.)  The  weight  of  the  maul  is  from  80  to  100  pounds  and  is 


FIG.  98. — STEAM     POWER    WELL 

worked  by  three  men  giving  it  a  lift  of  about  2  feet,  the  best  results  being 
obtained  when  the  men  act  in  concert  and  give  rapid  blows.  The  removal 
of  the  core  and  samples  is  accomplished  by  means  of  the  various  tools  shown 


124 


THE  COFFER-DAM  PROCESS  FOR  PIERS. 


in  Fig.  99,  and  requires  great  care  and  considerable  experience.  The  pump 
was  raised  and  lowered  by  means  of  the  reel  attached  to  one  leg  of  the 
tripod,  and  its  distance  from  the  surface  noted  from  graduations  on  the  pump 
rod.  When  the  boring  is  completed  the  tube  is  withdrawn  by  a  system  of 
compound  levers,  assisted  by  a  set  of  differential  blocks  when  necessary,  as 
the  force  exerted  was  often  as  much  as  the  strength  of  the  pipe  at  the  joints. 
The  pebble  tongs  were  for  use  in  removing  large  pebbles  which  would  not 
enter'  the  pumps,  and  for  recovering  lost  tools  or  the 
pump  itself  in  case  of  becoming  detached. 

The  above  account  is  taken  from  the  report  of 
J.  W.  Nier,  Assistant  Engineer,  to  which  reference 
must  be  made  for  other  details. 

When  the  examination  of  the  site  has  been  com- 
pleted and  the  borings  finished,  the  form  of  founda- 
tions may  be  decided  upon,  due  weight  being  given 
to  good  foundations  and  to  the  allowable  expenditure. 
Should  the  obtaining  of  good  foundations  be  seen  to 
be  very  expensive,  long  spans  must  be  adopted  to  re- 
quire few  piers  in  the  river,  but  if  inexpensive  much 
shorter  spans,  with  more  piers  may  be  used. 

The  length  of  spans  for  a  least  cost  of  structure 
was  formerly  assumed  to  be  decided  when  the  cost  of 
one  span  was  made  equal  to  the  cost  of  one  pier,  and 
for  spans  of  certain  capacity  this  might  be  approxi- 
mately true,  but  a  very  neat  mathematical  solution 
of  this  problem  by  Alfred  D.  Ottewell,  Consulting 
Engineer,  was  published  in  the  Engineering  News  of 
December  14,  1889.  The  total  length  of  the  struc- 
ture in  feet  was  represented  by  /,  the  number  of  spans 
by  n,  the  length  of  one  span  in  feet  /-f-  n  by  s,  the 
cost  of  one  span  in  dollars  by  c,  the  cost  of  one  pier  in 
dollars  by^>,  the  total  cost  of  the  structure  in  dollars 
by  y,  while  a  and  b  are  constants.  ' 

From  the  estimated  cost  of  a  large  number  of  spans,  a  curve  of  costs  was 
plotted  and  the  following  equation  of  a  parabola  deduced  : 


c  =  a 


FIG.  100.  —  CLAMP  AND 


Since  there  are  n  spans  and  n   +  1   piers,  the  total  cost  of  the  structure 
would  be 


Then  by  substituting  the  value  of  c  from  (1),  reducing  and  making  the  first 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  125 

differential  coefficient  equal  to  zero  the  cost  of  one  pier  is  obtained,  which 
will  make  the  total  cost  of  the  structure  a  minimum  or 


Or  when  the  cost  of  a  pier  has  been  estimated,  the  economical  length  of 
span  may  be  found  by  a  transposition  of  the  above  formula  : 

s  =  y"ab  +  400  +  pb      (4) 

The  values  of  a  and  b  may  be  found  by  substituting  in  equation  (1)  com- 
puted values  of  the  cost  of  a  number  of  spans  for  an  actual  loading.  Values 
of  5,  p  and  c,  may  then  be  computed  and  tabulated  for  spans  from  100  feet 
upwards,  as  formula  (1)  is  not  true  for  shorter  lengths. 

In  an  actual  calculation  for  B.  &  O.  R.  R.  loading,  which  consists  of  two 
125-ton  engines  followed  by  a  4,000-pound  per  lineal  foot  trainload,  a  was 
found  equal  to  1950  and  b  to  3.05.  Assuming  a  case  where  the  length  of 
the  bridge  is  700  feet,  where  the  height  of  the  piers  will  average  25  feet, 
and  the  average  cost  of  piers  and  abutments  be  $4,310,  then  from  formula 
(4)  the  economical  span  will  be  found  equal  to  140  feet.  The  total  cost  of 
the  structure  will  be  found,  by  using  formula  (1),  and  the  cost  of  piers  as 
above,  to  be  $59,700.  While  with  only  four  spans  of  175  feet,  the  total  cost 
would  exceed  $60,  800,  and  with  six  spans  of  117  feet,  would  be  about  $61,  400. 

Should  there  be  any  doubt  as  to  the  ease  of  obtaining  foundations,  the 
prudent  engineer  might  deem  it  wise,  however,  to  build  the  four-span 
structure  and  avoid  the  risk  and  delay  which  would  be  caused  by  another 
foundation  in  the  river. 

After  deciding  upon  the  number  and  location  of  the  piers,  they  must  be 
designed  with  reference  both  to  their  being  as  slight  obstructions  to  the 
water  as  possible  and  to  their  architectural  appearance. 

The  design  of  piers  has  been  given  particular  attention  by  Geo.  S. 
Morison,  Consulting  Engineer,  whose  work  on  the  bridges  across  our  great 
rivers  is  notable  for  its  strength,  simplicity  and  finished  appearance.  In  a 
recent  lecture  he  describes  the  process  of  the  design  of  some  large  piers  : 
"Fourteen  years  ago  I  had  occasion  to  design  a  bridge  pier  for  a  bridge 
across  one  of  our  Western  rivers,  and  I  tried  to  make  an  ornamental  pier. 
When  the  plans  were  completed  I  did  not  like  them.  One  change  after 
another  was  made,  all  tending  to  simplicity.  Finally  the  plans  were  done. 
From  high  water  down,  the  pier  was  adapted  to  pass  the  water  with  the 
least  disturbance;  it  had  parallel  sides  and  the  ends  were  formed  of  two  cir- 
cular arcs  meeting.  Above  high  water  the  ends  were  made  semi-circular 
instead  of  being  pointed.  The  pier  was  built  throughout  with  a  batter  of 
one  in  twenty-four.  A  coping  two  feet  wider  than  the  body  of  the  pier  pro- 
jected far  enough  to  shed  water,  and  the  projection  was  divided  between 


<;.    101. — I'IKK    OK    OMAHA    IJRIIXIK,     UNION    PACIFIC. 


FHE  COFFER-DAM  PROCESS  FOR  PIERS. 


12; 


the  coping  and  the  course  below.  Another  coping  with  a  less  projection 
surmounted  the  pointed  ends  where  the  shape  was  changed.  It  was  as 
simple  a  pier  as  could  be  built,  and  in  every  way  fitted  to  do  its  duty.  I 
had  started  to  make  a  handsome  pier.  The  pier  that  was  exactly  what  was 
wanted  for  the  work,  was  the  only  one  that  satisfied  the  demands  of  beauty. 
Forty-three  piers  of  precisely  this  design  (no  change  having  been  made 
except  in  the  varying  dimen- 
sions required  for  different 
structures),  besides  eight  oth- 
ers in  which  only  the  lower 
parts  are  modified,  are  now  , 
standing  in  eleven  different 
bridges  across  three  great 
Western  rivers.  In  designing 
a  pier  it  must  be  remembered 
that  the  portion  of  the  pier 
below  the  water  has  more  to 
do  with  the-  free  passage  of 
the  water  than  that  above 
water.  In  a  deep  river  the 
model  form  of  the  pier  should 
begin  near  the  bottom  of  the 
river  and  not  at  low  water. 
Many  rivers  in  flood  time 
carry  a  great  amount  of  drift. 
A  pier  like  that  which  I  have 
described  catches  but  little  of 
this  drift.  If,  however,  a  rec- 
tangular foundation  termin- 
ates but  little  below  water,  that 
foundation  may  uoth  disturb 
the  current  and  catch  the  drift. ' ' 

The  piers  of  the  Omaha  bridge,  which  carries  the  Union  Pacific  across 
the  Missouri  river,  are  illustrated  in  Fig.  101,  and  were  constructed  as 
described  and  are  among  the  most  beautiful  piers  in  this  country. 

In  Europe,  where  money  is  more  lavishly  expended  on  great  works  of 
engineering,  piers  of  great  architectural  beauty  are  much  more  frequent. 
The  Russian  Government  railways,  which  have  seemingly  been  constructed 
without  regard  to  expense,  have  many  beautiful  examples  of  bridge 
masonry  and  piers;  the  view  of  one  of  them  (Fig.  102)  with  curved  ends, 
shows  the  elegant  and  massive  character  of  the  masonry.  While  extremely 


FIG.  102. — RUSSIAN  PIER,  RUSSIAN  STATE 
RAILWAYS. 


FIG.  lOo. — CRESY'S  EXPERIMENTS  ON  THE  FORM  OF  IMKKS. 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  129 

simple  in  design,  the  cut  stone  coping  and  the  moulded  corbel  course  below 
give  it  a  finish  which  cannot  be  surpassed. 

The  design  of  piers  for  strength  and  stability  is  fully  treated  in  Baker's 
Masonry  Construction,  but  some  experiments,  which  were  made  with  ref- 
erence to  the  proper  form  to  occasion  the  least  resistance,  will  be  quoted  at 
length  from  Cresy. 

The  introduction  of  piers  into  a  channel  gives  rise  to  a  great  disturbance 
in  the  velocity  and  flow  of  the  water.  Rapid  currents  are  formed  which 
cause  the  bed  of  the  stream  to  become  washed  and  the  foundations  to  be 
endangered;  eddies  are  created  which  are  likewise  undesirable,  and  it 
becomes  necessary  to  adopt  such  a  form  for  the  ends  of  the  piers  that  the 
disturbance  to  the  flow  shall  be  small. 

M.  Bossut,  in  a  French  work  on  jetties,  thought  to  have  solved  this 
problem  by  mathemathics,  his  conclusion  being  that  the  starling  should  be 
triangular,  the  nose  being  a  right  angle. 

M.  Dubuat,  in  his  "Principles  of  Hydraulics,"  gave  another  solution 
which  was  more  nearly  the  truth,  in  that  he  arrived  at  the  conclusion  that 
the  faces  of  the  starling  should  be  convex  cnrves.  The  true  form  is  most 
nearly  reached  when  these  curves  are  tangent  to  the  sides  of  the  pier,  and 
further  than  this,  regard  must  be  paid  to  giving  enough  solidity  to  the 
starlings  to  protect  them  from  ice  and  drift.  A  happy  medium  would  seem 
to  be  reached,  by  making  the  curves  with  a  radius  equal  to  one-sixth  of  the 
circumference,  described  on  the  sides  of  an  equilateral  triangle. 

Experiments  were  made  with  models  of  different  forms,  which  were 
placed  in  a  rectangular  canal  between  boards  of  50  centimeters  in  length,  in 
which  the  water  flowed  about  40  millimeters  in  height,  the  models  being  15 
centimeters  in  thickness.  By  means  of  a  fall,  the  water  was  given  a  velocity 
of  3  meters  9  centimeters  per  second,  the  contraction,  eddies  and  currents 
being  carefully  measured.  The  first  experiment  was  made  on  a  pier  (Fig. 
103 A)  with  rectangular  starling.  An  eddy  was  formed  before  the  pier  34 
millimeters  high,  in  a  nearly  circular  band  A,  falling  nearly  vertical  at  the 
corner.  There  were  two  other  currents  along  the  faces  of  the  pier,  the  height 
of  which  can  be  seen  in  the  cross-sections. 

The  second  experiment  (Fig.  103B)  was  with  a  triangular  starling,  the 
nose  being  a  right  angle.  It  formed  a  less  obstruction  than  the  square  end, 
but  the  fall  at  the  shoulder  was  as  deep  and  more  dangerous,  while  eddies 
were  formed  as  seen  in  the  sections. 

The  third  one  (Fig.  103C)  had  a  semi-circular  starling.  The  eddy  was 
not  so  wide,  but  nearly  as  high. 

The  fourth  model  had  a  triangular  starling,  with  an  angle  of  60  degrees 
at  the  nose.  (Fig.  103D.)  The  eddy  was  less,  as  was  also  the  fall  at  the 
shoulder. 


130 


THE   COFFER-DAM  PROCESS  FOR  PIERS. 


The  starling  in  the  fifth  was  formed  by  two  circular  arcs,  tangent  to  the 
sides  and  described  on  the  sides  of  an  equilateral  triangle.  (Fig.  103E.) 
The  eddy  was  small  and  there  was  no  fall  at  the  shoulder. 


FIG.    104. — CRESY'S    EXPERIMENTS  ON  THE  FORM   OF  PIERS. 

The  sixth  (Fig.  103F)  was  a  model,  the  plan  of  which  was  an  ellipse,  of 
which  the  small  diameter  was  one-fourth  the  length,  and  the  eddy  was  less 
than  any  of  the  others. 

The  seventh  model  (Fig.  104 A)  had  a  starling  with  concave  faces,  such 
as  is  sometimes  used  where  the  wing  wall  meets  an  abutment.  It  produced 
the  most  dangerous  currents  of  all. 


THE  COFFER-DAM  PROCESS  FOR  PIERS.  131 

The  eighth  (Fig.  104B)  was  of  the  same  form  as  Fig.  103E,  but  the 
water  was  supposed  to  mount  the  springing  of  the  arch. 

The  ninth  and  tenth  experiments  (Figs.  104C  and  104D)  were  on  the 
same  forms  as  Figs.  103E  and  103F,  but  the  current  had  a  velocity  of  4 
meters  87  centimeters  per  second,  such  as  a  river  would  have  in  its  overflow. 
The  eddy  (Fig.  104C)  rose  to  nearly  twice  the  height,  as  was  the  case  with 
the  lesser  velocity,  and  while  there  was  no  fall,  the  inclination  formed  along 
the  faces  was  more  rapid. 

The  effect  with  this  velocity  on  the  elliptical  pier  (Fig.  104D)  was  sim- 
ilar to  the  lesser  velocity  but  more  marked.  It  may  thus  be  concluded  that 
the  elliptical  section  offers  the  least  resistance  to  the  current  and  occasions 
the  least  contraction,  while  the  form  with  convex  starling  comes  next,  and 
of  piers  with  triangular  starlings  the  one  with  the  60-degree  nose  is  the  best. 

Where  ice  is  to  be  provided  for,  the  nose  is  often  inclined  to  allow  large 
cakes  to  mount  it  and  break  in  two,  without  doing  further  damage.  For 
any  large  or  important  structure,  the  design  of  the  piers  should  receive  a 
great  deal  of  study,  and  be  designed  not  only  with  reference  to  their  theo- 
retical form,  but  with  reference  to  the  form  of  pier  which  has  shown  the  best 
results  practically  and  has  been  found  to  be  best  suited  to  the  velocity  of  the 
stream  in  which  they  are  to  be  built,  and  to  best  withstand  the  drift  and  ice 
that  may  be  met  with,  giving  at  the  same  time  all  the  consideration  possible 
to  the  architectural  effect  and  to  the  harmony  with  the  entire  structure. 


APPENDIX. 


SELECTIONS  FROM   SPECIFICATIONS. 


SPECIFICATIONS  FOR  COFFER-DAMS  AND  FOUNDATIONS, 
OHIO   RIVER  MOVABLE  DAMS. 

MAJOR  W.   H.    HEUER,   U.  S.   Engineer. 

GENERAL  DESCRIPTION. 

The  site  of  Dam  No.  2  is  on  the  Ohio  River,  distant  from  Pittsburg,  Pa.,  ioi  miles, 
and  adjacent  on  the  right  bank  to  the  Pittsburg,  Ft.  Wayne  and  Chicago  Railway.  It 
has  Neville  Island  on  the  left  bank,  and  is  accessible  by  street  cars  from  Pittsburg. 

The  lock  is  to  be  located  on  the  left  bank  of  the  Ohio  River,  immediately  behind 
Merrimans  dyke.  It  will  be  in  general  dimensions  the'  same  as  locks  Nos.  i  and  6, 
viz.,  no  feel  wide  and  600  feet  long. 

SPECIAL  DESCRIPTION. 

The  river  bed  at  No.  2  consists  of  gravel  throughout,  and  the  excavations  will  be 
made  to  a  depth  sufficient  to  insure  a  permanent  and  enduring  foundation,  which  will 
ordinarily  be  14  feet  below  the  gate  sill,  but  may  be  otherwise,  as  the  Engineer,  in  his 
judgment,  may  direct. 

The  work  will  conform  to  the  drawingsexhibited,  and  to  such  others,  in  explanation 
of  details  or  modifications  of  plans,  as  may  be  furnished  from  time  to  time  during  con- 
struction. 

CONTRACTOR  TO  FURNISH  ALL  MATERIAL  AND  WORK. — It  is  understood  and  agreed 
that  the  contractor,  under  his  contract  prices  for  work  in  place,  is  to  furnish  and  pay 
for  all  materials,  stone,  cement,  sand,  earth,  timber,  material  for  coffer-dam  and  protec- 
tion cribs,  excavation,  lock-filling  and  discharging  valves  (set  in  masonry),  flushing 
valves,  anchor  bolts,  lock-gate  tracks,  and  everything  entering  into  or  connected  with 
either  the  permanent  or  temporary  construction,  and  he  is  also  to  supply  and  pay  for  all 
work:  skilled  and  otherwise,  required  to  prepare  and  place  the  materials,  and  complete 
the  work  according  to  the  drawings  and  these  specifications. 

CONTRACT  TO  INCLUDE — The  contract  will  cover  the  construction  and  completion  of 
the  foundation,  masonry  and  timber  work  of  the  lock,  including  both  land  and  river 
walls,  the  gate-recess  walls,  the  foundations  of  the  lock-gate  tracks,  the  guiding  walls 
above  and  below  the  lock,  the  pipe  and  flushing  conduits,  the  drift  chute,  the  founda- 

133 


134  APPENDIX 

tions  for  the  power-house  and  lock-keepers'  residence,  and  every  such  other  permanent 
construction  as  shall  be  shown  upon  the  drawings.  It  shall  also  include  the  clearing 
of  the  land  necessary  for  the  proper  execution  of  the  work  embraced,  in  this  contract, 
all  pumping  and  bailing,  dredging  and  excavation,  puddling  and  embankment,  the  con- 
struction of  all  coffer-dams,  stone  masonry,  concrete  and  brick  masonry,  timber  work 
and  iron  work,  and  all  such  other  work  which,  in  the  judgment  of  the  Engineer,  is  nec- 
essary and  included  in  the  proper  completion  of  the  contract. 

TOOLS,  MACHINERY,  BUILDINGS,  ETC. — The  contractor,  without  cost  to  the  United 
States,  shall  furnish  all  appliances,  dredges,  pumps  and  pumping  machinery,  boats, 
tools,  derricks,  tramways,  foot  walks,  roads  and  landings,  and  all  needful  temporary 
buildings  and  shops. 

COFFER-DAM. 

SHEETING. — The  coffer-dam,  about  1500  feet  in  length,  shall  be  built  as  shown  gen- 
erally by  the  drawings  exhibited,  and  as  directed  by  the  Engineer.  It  shall  be  14  feet 
high  above  the  sill  of  the  lock,  and  shall  consist  of  two  walls  or  rows  of  plank  sheeting, 
spaced  12  feet  apart  in  the  clear,  driven  or  set  firmly  from  i  to  2  feet  into  the  river  bed, 
and  supported  laterally  by  horizontal  longitudinal  stringers,  the  latter  being  spaced 
at  varying  intervals,  increasing  in  width  from  the  bottom  to  the  top,  and  to  be  suffi- 
ciently and  firmly  bolted  together  transversely  with  iron  rods  passing  through  the 
coffer-dam  horizontally  from  the  rows  of  stringers  on  the  one  side  to  the  corresponding 
rows  on  the  other,  against  which  the  vertical  plank  sheeting  shall  be  securely  spiked. 

FILLING  AND  DECKING. — The  interior,  or  space  between  the  walls  of  sheeting,  shall 
be  filled  with  heavy  dredged  river-bed  or  other  material  not  liable  to  wash,  and  to  be 
covered  over  with  a  suitable  decking  of  plank  (to  protect  it  from  injury  in  case  of  being 
submerged  by  floods),  all  complete  as  shown  on  the  drawings. 

PILING  AND  CRIBS  TO  PROTECT. — At  the  upper  outer  corner  of  the  coffer-dam  shall 
be  placed  a  crib  built  of  framing  timber  and  filled  with  riprap  stone  ;  from  the  upper 
corner  of  the  crib,  at  an  angle  of  45°  with  the  axis  of  the  current,  a  line  of  piling,  spaced 
5  feet  apart,  firmly  bolted  together  with  waling  pieces,  shall  be  driven  to  the  shore  to 
form  a  protection  to  the  coffer-dam  ;  also  outside  and  along  the  coffer-dam,  from  the 
upper  outer  corner  to  the  lower  corner,  clusters  of  piles,  firmly  bound  or  bolted 
together,  shall  be  driven  at  intervals  of  about  80  feet.  The  tops  of  all  piling  shall  be 
sawed  off  to  a  uniform  height,  of  2  feet  above  the  coffer-dam.  Protection  cribs  shall  be 
placed  at  such  other  points  along  the  coffer-dam  as  may  be  shown  upon  drawings. 

How  PAID  FOR. — Bidders  will  state  a  price  per  lineal  foot  of  coffer-dam  completed. 
No  payment  will  be  made  for  any  portion  thereof  until  the  entire  coffer-dam  is  completed. 
Drawings  will  be  furnished,  showing  the  general  type  of  the  coffer-dam  and  its  manner 
of  construction,  and  every  detail  necessary  for  intelligent  bidding.  Should  any  work 
on  the  outside  of  the  coffer  be  necessary,  such  as  gravel  filling  or  riprapping,  it  shall 
be  paid  for  at  the  price  bid  for  gravel  filling,  riprapping,  etc.  If,  owing  to  the  nature 
of  the  river  bed,  it  shall  be  found  impossible  to  drive  the  plank  sheeting  to  the  required 
depth,  then  the  contractor,  after  driving  the  sheeting  as  deep  as  possible  without  injury, 
and  in  lieu  of  driving  it  to  its  full  depth,  shall  fill  around  the  outside  of  the  walls  with 
the  same  material  as  is  used  in  filling  the  coffer-dam,  to  the  height  of  4  feet  above  the 
surface  of  the  river  bed,  and  for  which  no  extra  compensation  will  be  allowed. 

REMOVAL  OF. — The  contractor  will  be  required  to  remove  the  coffer-dam  and  its  be- 
longings at  his  own  cost.  The  time  and  manner  of  the  removal  of  the  coffer-dam,  or 
any  part  thereof,  and  the  place  to  deposit  the  materials,  shall  be  prescribed  by  the 
Engineer. 

To  BELONG  TO  THE  UNITED  STATES. — It  is  understood  and  agreed  that  the  payments 
made  for  the  coffer-dam,  including  the  crib  and  pile  protection,  shall  cover  the  entire 
cost  thereof  to  the  United  States,  and  by  virtue  thereof  they  shalj  become  the  property 
of  the  United  States.  The  contractor,  however,  must  maintain  the  same  and  make  all 
needed  repairs  to  same  during  the  existence  of  the  contract,  without  expense  to  the 
United  States. 

DEPOSIT  WITHIN  THE  COFFER-DAM. — Material  washed  or  left  in  the  space  enclosed 
by  the  coffer-dam  by  freshets  shall  be  removed  by  the  contractor,  as  directed,  at  his 
price  for  common  excavation,  which  price  shall  cover  all  necessary  cleaning  and  scrub- 
bing. No  payment  will  be  made,  however,  for  removing  material  washed  into  the  enclos- 


APPENDIX.  135 

lire  from  the  coffer-dam  itself  or  from  any  deposit  made  by  the  contractor  on  or  above 
the  works. 

MATERIAL  AND  WORKMANSHIP. 

TEMPORARY  PILING  shall  include  all  piles  driven  for  the  protection  of  the  coffer- 
dam and  "deadmen"  for  derricks.  They  shall  be  of  good  quality,  round  oak  timber, 
not  less  than  12"  diameter  at  the  butt,  and  of  length  varying  from  20  to  25  feet,  and 
longer  if  necessary. 

SHEET  PILING. — In  excavating  for  foundations,  should  quick-sand  or  fine-sand- 
carrying  water  be  encountered,  close  sheet  piling  will  be  required  to  be  driven  to  what- 
ever extent  the  Engineer  may  direct. 

SHEETING. — The  sheeting  shall  include  the  walls  and  decking  of  the  coffer-dam,  in- 
cluding the  stringers  ;  also  such  shoring  as  may  be  directed  by  the  Engineer  to  remain 
in  the  finished  structure.  It  shall  consist  of  the  best  quality  of  hemlock  obtainable, 
and  must  be  in  all  cases  satisfactory  to  the  Engineer  in  charge. 

GRAVEL  OR  EARTH  FILLING. — Gravel  or  earth  filling  will  include  all  material  used  in 
filling  the  land-wall  enclosure,  back  of  the  guiding  walls,  etc.  It  does  not  include  any 
filling  in  the  construction  of  the  coffer-dam. 

STONE  FILLING  shall  include  all  stone  placed  in  the  protection  cribs  or  any  riprap 
stone  ordered  for  the  protection  of  the  work. 

CRIB  WORK  shall  be  built  of  hemlock  framing  timber  framed  together  in  square 
bins  and  securely  bolted  together  by  iron  drift-bolts.  The  interior  of  the  cribs  shall  be 
filled  with  riprap  stone,  and  should  the  Engineer  deem  it  necessary  such  riprap  stone 
shall  be  placed  on  the  outside  of  the  crib.  The  whole  to  be  built  as  shown  by  the 
drawings. 

FRAMING  TIMBER. — For  all  temporary  crib  work,  also  the  permanent  crib  at  the  head 
of  the  upper  guiding  wall,  framing  timber  shall  be  used.  No  stick  shall  be  less  than 
10"  X  10''  in  section. 

"  Framing  timber  "  is  a  commercial  term  for  a  class  of  timber  hewn  to  various  sizes. 

EXCAVATION. 

To  INCLUDE. — It  shall  include  the  removal  of  all  gravel  or  other  material  to  the 
depth  required  for  the  lock  and  its  upper  and  lower  entrances,  the  gate  recesses,  Poiree- 
dam  and  gate-track  foundations,  for  the  foundations  of  all  walls,  and  for  all  conduits  or 
wells,  and  all  such  other  material  as  may  be  found  necessary  in  the  judgment  of  the 
Engineer  to  be  removed  for  foundations  and  otherwise  in  permanent  construction.  It 
will  include  all  dredging  and  all  material  excavated  of  whatever  nature,  however 
removed,  for  foundations  and  for  site  of  coffer-dam. 

LINES,  SLOPES,  AND  GRADES  FOR. — All  excavations  shall  conform  to  such  lines,  slopes, 
and  grades  as  may  be  given  by  the  Engineer,  and  anything  taken  out  beyond  such 
given  limits  will  not  be  paid  for  by  the  United  States. 

MATERIAL  TO  BE  DEPOSITED. — Excavated  material  is  to  be  deposited  as  and  where 
directed  by  the  Engineer.  It  shall  be  deposited  in  such  manner  as  not  to  interfere 
with  present  or  proposed  navigation.  Material  of  any  kind  deposited  by  the  contractor 
in  absence  of,  or  in  disregard  of.  instructions,  shall,  if  required  by  the  Engineer,  be 
removed  by  the  contractor  at  his  own  cost. 

SHORING. — All  excavation  for  foundation  shall  be  securely  shored  and  thus  main- 
tained until  the  foundation  has  been  sufficiently  advanced  to  dispense  with  the  same, 
when  it  may  remain  or  be  removed  at  the  discretion  of  the  Engineer. 

DREDGF.S  AND  PUMPS. — The  contractor  will  be  required  to  employ,  at  the  same  time, 
not  less  than  two  suitable  steam  dredges  at  excavating  and  filling;  and  for  pumping 
he  must  keep  at  least  three  good  sufficient  pumping  outfits,  with  pumps,  engines,  and 
boats  complete,  in  or  always  ready  for  operation.  The  dredges  must  be  equipped  to  do 
effective  work  to  a  depth  of  28  feet. 


APPENDIX. 


FOUNDATIONS. 

CHANGES  OR  MODIFICATIONS  OF. — The  character  of  the  river  bed  and  of  the  proposed 
foundations  for  the  different  parts  of  the  work  is  shown  in  general  on  the  drawings  and 
cross-sections  exhibited,  and  it  is  understood  that  the  United  States  shall  have  the 
power  to  make  any  changes  in  the  plans  of  the  foundations  that  may,  in  the  judgment 
of  the  Engineer,  be  considered  advisable  after  examinations  made,  as  the  excavations 
proceed  within  the  coffer-dam  after  it  is  pumped  out  and  it  is  understood  and  agreed 
that  the  contractor  shall  have  or  make  no  claim  against  the  United  States  on  account 
of  any  such  changes  in  or  modifications  of  the  plans  of  the  foundations,  or  on  account 
of  any  increase  or  decrease  in  the  depth  of  same,  under  or  over  those  referred  to  herein 
or  shown  on  the  drawings  exhibited. 

MASONRY. 

CEMENT. — Cement  will  be  of  uniform  quality,  setting  well  both  in  air  and  water,  and 
free  from  anything  that  will  cause  the  mortar  to  swell,  crack,  or  scale.  It  shall  be  put 
up  in  strong,  sound  barrels,  well  lined  with  paper  so  as  to  be  reasonably  protected  from 
air  and  moisture.  The  average  net  weight  of  the  barrels  shall  be  not  less  than  265 
pounds,  unless  expressly  so  stated  in  the  proposal.  Each  barrel  must  be  labeled  with 
the  name  of  the  brand  and  of  the  manufacturer. 

In  general,  ten  barrels  of  every  one  hundred  will  be  tested. 

The  cement  must  stand  .the  following  tests  ;  Fineness — At  least  85  per  cent  must 
pass  a  sieve  of  6400  meshes  to  the  inch.  Setting — Cement  must  be  moderately  slow 
setting  ;  it  must  not  begin  to  set  within  fifteen  minutes,  as  determined  by  Vicat  needle 
1/12  inch  in  diameter  with  1/4  pound  load,  and  it  shall  not  bear  the  weight  of  one 
pound  on  wire  1/24  inch  in  diameter  within  thirty  minutes,  but  must  bear  such  weight 
within  one  hour  and  a  half.  Strength — The  minimum  tensile  strength  per  square  inch 
of  briquettes  of  neat  cement  mixed  with  about  33  per  cent  of  water  by  weight,  and 
exposed  in  air  for  one  hour,  and  the  remainder  of  24  hours  in  water,  shall  be  not 
less  than  50  pounds  ;  with  longer  time,  whether  in  air  or  water,  there  must  be  a 
decided  increase  of  strength  ;  it  must  also  test  to  the  satisfaction  of  the  Engineer  when 
mixed  with  sand.  The  tests  for  setting  will  be  made  at  a  temperature  of  air  and  water 
of  about  75°  Fahrenheit.  All  other  tests  will  be  made  at  a  temperature  above  6o3 
Fahrenheit.  The  cement  will  be  subject  to  inspection  at  all  times,  and  must  be  kept 
well  housed. 

SAND. — The  sand  used  must  be  clean,  sharp,  washed,  river  sand,  satisfactory  to 
the  Engineer. 

MORTAR. — To  be  composed  generally  of  two  parts  of  sand  to  one  of  cement  ;  when 
required,  and  whenever  thought  necessary  by  the  Engineer,  it  shall  be  made  richer. 
It  must  be  thoroughly  mixed  and  used  before  it  has  begun  to  set.  If  required  by  the 
Engineer,  the  mortar  beds  will  be  protected  from  the  sun. 

POINTING.' — All  face  work  is  to  be  pointed,  as  fast  as  the  work  progresses,  with  stiff 
mortar,  mixed,  one  of  sand  to  one  of  Portland  cement,  thoroughly  hammered  in  and 
finished  with  proper  tools  ;  before  the  final  acceptance  ot  the  work  all  face  masonry 
which  at  that  time  does  not  appear  properly  pointed  shall  be  repointed  by  the  con- 
tractor to  the  satisfaction  of  the  Engineer,  without  extra  cost. 

FROST. — Masonry  will  not  be  executed  during  freezing  weather,  nor  when,  in  the 
judgment  of  the  Engineer  or  his  agent,  it  is  likely  to  fieeze  before  the  rnortar  shall 
set.  To  guard  against  injury  from  frost  all  new  a^nd  unfinished  work  shall  be  properly 
protected  by  the  contractor  at  his  own  cost. 

VOIDS  AND  OPENINGS. — Due  regard  shall  be  had  in  the  construction  of  all  masonry 
wralls  to  leave  all  necessary  voids  or  openings  for  conduits  or  wells,  or  for  such  other 
purposes  as  may  be  required  by  the  Engineer. 

ASHLAR. — It  shall  comprise  such  part  of  the  walls  as  is  built  of  stone,  with  point- 
dressed  face,  and  beds  and  joints  smoothly  and  squarely  dressed. 

QUALITY  OF  STONE.  —  All  stone  shall  be  perfectly  sound,  strong,  hard,  free  from  in- 
jurious seams,  and  in  all  respects  satisfactory  to  the  Engineer.  Stone  to  be  such  as 


APPENDIX.  137 

can  be  truly  wrought  to  such  Hues  and  surfaces,  whether  curved  or  plain,  as  may  be  re- 
quired.     No  stone  shall  be  used  which  weighs  less  than  135  pounds  to  the  cubic  foot. 

SAMPLES  OF  STONE  — Each  bidder  must  deposit  at  this  office,  all  charges  prepaid, 
before  the  bids  are  opened,  a  6-inch  cubical  block  of  the  stone  he  proposes  to  furnish, 
and  state  the  quarry  from  which  it  was  obtained.  The  quality  of  the  stone  must  be  at 
least  equal  to  that  of  the  sample.  The  sample  must  be  truly  squared,  and  dressed  on 
four  sides  ;  one  side  must  be  hammer-dressed,  one  side  smooth-dressed  and  rubbed, 
and  one  side  pitch-dressed.  The  other  two  sides  are  to  be  left  with  quarry  face. 

STONE  MAY  BE  REJECTED. — The  United  States  reserves  the  right  to  reject  any 
stone  not  deemed  suitable,  or  which,  during  the  execution  of  the  contract,  shall  be 
found  defective.  The  beds  of  the  stone  must  be  their  natural  quarry  beds.  No  lewis 
or  dog  holes,  letters,  or  marks  of  any  kind  will  be  allowed  on  any  dressed  face  of  stone, 
but  each  face  shall  have  left  on  it  a  boss  for  lifting,  to  be  removed  by  the  contractor 
after  the  stone  has  been  set. 

DRESSING  OF  STONE. — Stone  must  be  accurately  cut,  square  and  true,  and  the  faces 
must  be  pitch  draughted  and  point-dressed  to  a  plane  with  the  draught,  forming  an 
approximately  smooth  surface.  The  beds  must  be  smoothly  and  squarely  dressed,  full 
length  and  width.  The  vertical  joints  must  be  dressed  to  a  depth  of  not  less  than  18 
inches  from  the  face,  and  the  allowance  for  joints  must  not  exceed  3/8  inch.  One- 
third  of  the  stone  in  each  course  must  be  headers.  All  stones  not  accurately  dressed 
will  be  rejected.  All  dressed  stone  must  have  the  dimensions  plainly  marked  on  one 
end. 

DIMENSIONS. — The  cut-stone  stretchers  must  be  not  less  than  3  feet  nor  more  than  5 
feet  long,  and  their  width  must  be  not  less  than  \\  times  the  height  of  the  course  to 
which  they  belong.  The  width  of  the  headers  must  be  not  less  than  \\  times  their 
height,  and  their  length  must  be  at  least  double  their  breadth,  unless  otherwise 
ordered.  The  thickness  of  courses  includes  the  joint,  which  will  be  3/8  inch.  . 

LAYING  STONE  MASONRY. — The  faces  of  the  walls  shall  be  accurately  laid  to  the 
lines  indicated  on  the  drawings,  or  as, directed  by  the  Engineer.  All  stones  to  be  well 
laid  to  proper  lines,  in  full  beds  of  mortar,  and  settled  in  place  with  a  wooden  maul  ; 
the  use  of  grout  is  prohibited.  No  dressing,  except  in  special  cases,  and  by  permission 
of  the  Engineer,  will  be  allowed  on  backing  after  it  is  laid  in  the  wall.  The  bond  of 
stone  shall  in  no  case  be  less  than  9  inches.  The  walls  will  be  laid  in  horizontal 
courses  throughout,  each  course  to  be  of  uniform  height  through  the  wall.  Heights 
and  arrangements  of  courses  to  be  determined  by  the  Engineer.  When  laying  masonry 
the  site  for  the  stone  shall  be  thoroughly  cleaned  with  a  scrub  broom  and  moistened  ; 
and  the  stone  shall  always  be  cleaned  and  well  moistened  before  being  set.  Not  more 
than  three  unfinished  courses  of  face  stone  will  be  permitted  upon  the  wall  at  the  same 
time,  without  special  permission  from  the  Engineer  in  each  case.  Proper  machinery 
must  be  used  in  handling  the  stone  ,  face  stone  shall  not  be  disfigured  by  use  of  plug 
or  grabs.  Any  stone  chipped  or  spalled  shall  be  rejected.  Stones  having  defects  con- 
cealed by  cement  or  otherwise  will  be  rejected  on  that  account  alone. 

COPING.  — The  coping  will  be  of  the  same  class  and  quality  of  stone  described  in 
ashlar  masonry.  It  will  be  carefully  and  truly  cut  to  forms  and  dimensions  given, 
from  the  best  stone  ,  it  will  be  cranda'lled  on  all  outer  faces  ;  the  exposed  edges  of  the 
coping  to  be  rounded  to  a  radius  of  3  inches  and  chiseled  smooth  where  required. 
Beds  and  vertical  joints  to  be  pointed  true  and  full  throughout  and  be  laid  with  3/8- 
inch  joints. 

The  coping  is  to  be  doweled  as  required  by  the  Engineer  with  round  iron.  The 
dowels  to  be  furnished  and  placed  by  the  contractor.  The  drilling  for  and  placing  of 
the  dowels  will  be  covered  by  the  price  for  "  Bolt  Holes  in  Masonry."  The  dowels  will 
be  set  in  Portland  cement. 

RUBBLE    STONE. 

QUALITY  AND  DIMENSIONS  OF.  — Rubble  stone  must  be  sound,  hard,  and  durable, 
free  from  seams,  scale,  earthy  matter,  and  other  defects.  Rubble  stone  shall  in  gen- 
eral be  not  less  than  3/4  of  a  cubic  foot  in  size.  It  must  be  in  fair  shape  for  laying  in 
the  face  of  the  walls  without  dressing.  No  spalls  will  be  allowed. 

LAYING. — The   stone   must   be   laid   on   their   natural   bed    in   full  beds  of  hydraulic 


138  APPENDIX. 

cement  mortar,  with  all  joints  and   voids  well  filled  with   mortar.      Leveling  up  under 
stones  with  small  chips  or  spalls  will  not  be  allowed. 

The  stone  shall  be  carefully  selected  for  the  outer  face  so  as  to  have  vertical  joints 
and  present  a  good  face  of  broken  rough  masonry. 

CONCRETE. 

COMPOSITION  OF. — Concrete  shall  be  composed  of  satisfactory  cement  and  river 
gravel  ;  the  latter,  should  it  be  of  an  approved  quality,  shall  be  taken  from  the  various 
excavations  of  the  lock  and  its  walls.  This  gravel  generally  has  a  sufficient  volume 
of  sand  to  fill  all  voids  ,  should  there  be  a  deficiency  of  sand  in  any  portion  of  the 
gravel  the  contractor  will  be  required  to  supply  said  deficiency  by  good,  sharp,  washed, 
river  sand.  The  quantity  of  cement  to  be  used  will  generally  be  about  20  per  cent 
greater  than  the  volume  of  voids  in. sand  and  gravel. 

MIXING  AND  PLACING  OF. — The  concrete  is  to  be  well  and  rapidly  mixed  by 
machinery,  as  may  be  required  by  the  Engineer,  unless  otherwise  specified.  It  will  be 
deposited  in  layers  not  more  than  8  inches  thick  ;  wherever  and  whenever  required, 
the  layers  will  be  thinner  than  8  inches,  and  all  thoroughly  rammed  by  such  process 
as  the  Engineer  may  approve. 

RIVER  WALL. — In  the  river  wall  of  the  lock  the  concrete  shall  be  laid  in  courses  of 
a  thickness  corresponding  to  the  adjoining  courses  of  ashlar  masonry.  It  shall  be 
filled  in  flush  with  the  top  of  each  course  before  the  next  course  of  ashlar  above  shall 
be  laid. 

Before  putting  in  the  concrete  of  any  course  the  bed  and  adjoining  course  of  ashlar 
shall  be  thoroughly  wetted  so  that  no  dry  surface  may  come  in  contact  with  the  fresh 
concrete,  destroying  its  power  of  adhesion  by  absorbing  its  moisture. 

In  order  that  the  work  once  begun  may  progress  without  delay  all  cut  stone 
needed  for  the  ashlar  facing  shall  be  on  the  ground  when  the  concrete  foundation  has 
been  completed. 

TIMBER    IN    PERMANENT    CONSTRUCTION. 

To  CONSIST  OF  all  timber  used  in  the  timber  facing  of  the  lock  walls  and  the 
guide  walls  ;  all  timber  cribbing  in  the  gate-track  and  Poiree  dam  foundations  ;  the 
oak  sheeting  at  the  head  of  the  guide  walls  ;  and  such  other  timber  in  permanent  con- 
struction as  shall  be  shown  upon  the  drawings. 

GENERAL  QUALITY  AND  DIMENSIONS. — All  timber  must  be  first  class,  and  any  of 
inferior  quality  will  be  rejected.  Sap-wood  in  any  stick  will  cause  its  rejection.  The 
timber  must  be  free  from  black  or  rotten  knots,  wane  edges,  wind  shakes,  dose,  or 
other  imperfections.  Firm  sound  knots,  if  not  too  numerous,  will  not  be  considered 
defects.  Timber  must  be  full  to  size,  true,  and  out  of  wind,  and  when  required  must 
be  sawed  large  enough  to  dress  down  to  required  dimensions.  The  timber  will  be 
inspected  on  arrival  at  the  work,  and  if  found  to  be  defective  will  be  rejected. 

OAK. — Oak  timber  must  be  taken  from  the  best  quality  live  white  oak  sawed  timber. 

WHITE  PINE. — Shall  consist  of  the  best  quality  of  clear  white  pine  obtainable. 

HEMLOCK. — Shall  be  the  best  quality  of  hemlock  obtainable. 

FRAMING,  ASSEMBLING,  AND  PAINTING. — All  timber  must  be  accurately  framed, 
fitted,  and  assembled,  according  to  detailed  drawings  and  directions.  As  the  timber 
is  framed  it  shall  be  painted  about  the  ends  and  elsewhere  as  may  be  required  to  pre- 
vent checking.  The  paints  for  this  will  be  furnished  and  applied  by  the  contractor, 
and  covered  in  his  price  for  "  Timber  in  Permanent  Construction  " 

TIMBER  FACING,  UPRIGHTS.  AND  SHEETING  shall  be  constructed  of  oak,  and  shall 
consist  of  uprights  spaced  at  intervals  of  6  feet,  center  to  center,  anchored  to  the  con- 
crete masonry  by  tee-head  screw  bolts  as  shown  on  drawings.  To  the  uprights  shall 
be  bolted,  with  wrought-iron  screw  bolts,  oak  sheeting  6  inches  thick. 

NOSING  TIMBER  shall  extend  along  the  top  of  the  guide  wall,  forming  a  cap  to  the 
uprights  and  securely  bolted  to  them,  as  shown  on  the  drawings.  The  top  surface  of 
the  nosing  shall  be  flush  with  the  top  of  the  concrete  masonry  wall. 

OAK  SHEETING. — This  refers  to  the  sheeting  on   the   upper  faces  of  the  protection 


APPENDIX.  139 

crib  for  the  upper  guiding  wall  at  the  upper  end  thereof.  It  shalf  be  spiked  on  and 
firmly  held  in  place  with  iron  bands  or  straps  bolted  to  the  framing  timbers  of  the  crib, 
if,  in' the  judgment  of  the  Engineer,  this  may  be  deemed  necessary. 

SUPERVISION    AND    MEASUREMENT    OF    WORK. 

INSPECTION,  REJECTED  MATERIAL,  ETC. — The  works  will  be  conducted  under  the 
direction  of  the  local  or  resident  Engineer,  who  shall  have  power  to  prescribe  the  order 
and  manner  of  executing  the  same  in  all  its  parts  ;  of  inspecting  and  rejecting  ma- 
terials, work,  and  workmanship  which,  in  his  judgment,  do  not  conform  to  the  draw- 
ings that  may  be  furnished  from  time  to  time,  or  to  these  specifications.  And  any 
material,  work,  or  workmanship  so  rejected  by  him  shall  be  kept  out  of  or  removed 
from  the  finished  work,  and  no  estimate  or  payment  shall  be  made  until  such  material, 
work,  or  workmanship  be  so  removed. 

When  so  required  rejected  material  shall  be  piled  up  in  sight  near  the  works  and 
kept  there  until  the  Engineer  gives  permission  to  have  it  removed. 

The  United  States  will  keep  inspectors  on  the  work  who  will  receive  instructions 
from  the  resident  Engineer.  They  will  have  power  to  object  to  any  materials,  work, 
or  workmanship.  Any  material,  work,  or  workmanship  objected  to  by  the  inspectors 
shall  be  kept  out  of  or  removed  from  the  finished  work,  unless  in  each  particular  case  the 
objections  of  the  inspector  shall  be  overruled  by  the  local  or  resident  Engineer  ;  and, 
unless  the  objection  be  so  overruled,  no  estimate  or  payment  shall  be  made  until  such 
material,  work,  or  workmanship  be  so  removed. 

The  local  or  resident  Engineer  shall  have  power  to  overrule  or  rescind  any  or  all 
objections  or  decisions  of  the  inspector. 

The  decision  of  the  United  States  Engineer  Officer  in  charge  of  the  works  shall  be 
final  and  conclusive  upon  all  matters  relating  to  the  work  and  upon  all  questions 
arising  out  of  these  specifications,  and  from  his  decision  there  shall  be  no  appeal. 

FAILURE  TO  PROSECUTE  OR  PROTECT  WORKS. — If  at  any  time  the  contractor  shall 
refuse  or  fail  to  prosecute  the  work  or  provide  for  carrying  on  the  same  as  directed  by 
the  Engineer,  or  fail  to  properly  protect  any  part  of  the  work,  permanent  or  tem- 
porary, the  Engineer  shall  have  power  to  employ  men,  to  purchase  or  otherwise  provide 
materials,  tools,  machinery,  etc.,  and  put  the  work  in  proper  advancement  or  condition, 
and  the  entire  cost  of  so  doing  shall  be  deducted  from  payments  to  be  made  under  this 
contract. 

COMPLETE  WORK  REQUIRED. — The  contractor  is  not  to  take  advantage  of  any 
omissions  of  details  in  drawings  or  specifications,  or  errors  in  either,  but  he  will  be 
required  to  do  everything  which  may  be  necessary  to  carry  out  the  contract  in  good 
faith,  which  contemplates  everything  complete,  in  good  working  order,  of  good 
material,  with  accurate  workmanship,  skillfully  fitted  and  properly  connected  and  put 
together.  Any  point  not  clearly  understood  is  to  be  referred  to  the  Engineer  for 
decision. 

CHANGES.  —  Should  any  changes  in  the  details  of  the  shape,  arrangement,  or  fitting 
of  the  parts  be  deemed  necessary  or  advisable  in  the  progress  of  the  work,  they  must 
be  made  by  the  contractor,  and  a  fair  allowance  will  be  paid  for  any  changes  which, 
in  the  judgment  of  the  Engineer  in  charge,  materially  increases  the  cost  of  the  work. 

MEASUREMENT. — Measurement  of  all  work  and  material  shall  be  made  in  place, 
unless  otherwise  specified. 

COFFER-DAM. — The  price  per  lineal  foot  of  coffer-dam  shall  include  all  material, 
lumber,  iron,  and  gravel  entering  into  its  construction.  A  profile  of  the  location  will 
be  furnished,  showing  a  section  of  the  river  bed  over  which  the  coffer-dam  is  located, 
so  that  the  contractor  may  estimate  the  amount  of  each  kind  of  material  required. 

PILING. — Temporary  piling  shall  be  measured  in  lineal  feet,  and  measurement  shall 
be  allowed  for  total  length  of  piling  used. 

SHEETING  — This  will  include  all  lumber  used  for  temporary  purposes,  in  shoring 
of  excavations,  or  for  forms  necessarv  to  sustain  any  concrete  masonry  until  it  has 
become  sufficiently  hardened.  Sheeting  required  by  the  Engineer  to  remain  in  the 
finished  structure  shall  be  paid  for  at  the  contractor's  price  per  thousand  feet  B.  M. 
All  temporary  sheeting  not  remaining  in  the  finished  structure  shall  be  included  in  the 
contractor's  unit  price  for  material  in  place,  and  no  estimate  will  be  made  thereof  by 


140  APPENDIX. 

the  Engineer.     Coffer-dam  sheeting  will  be  included  in  the  contractor's  price  per  lineal 
foot  of  coffer-dam. 

FILLING. — Gravel  filling  will  be  measured  in  the  fill,  and  will  not  include  any  filling 
placed  in  the  coffer-dam  as  coffer-dam  filling. 

Stone  filling  shall  include  all  riprap  work,  either  temporary  or  permanent. 

EXCAVATION. — Excavation  will  be  measured  in  excavation  by  cross-sections. 

MASONRY. — All  masonry,  ashlar,  rubble,  brick,  concrete,  etc.,  will  be  measured  by 
the  cubic  yard  in  place.  Prices  for  masonry  will  include  all  required  pointing.  No 
payment  will  be  allowed  for  voids  or  openings. 

BOLT  HOLES. — All  holes  drilled  in  rock  or  concrete  or  other  masonry  will  be 
measured  by  the  running  foot  as  drilled. 

TIMBER    IN    PERMANENT    CONSTRUCTION. — Timber    in   permanent   construction    will 
include   all  timber  used  in  any  part  of  the  permanent  construction  ;   unless  otherwise 
particularly  specified,  will  be  classed  under  the  following  heads  : 
Oak  in  Permanent  Construction. 
Pine  in  Permanent  Construction. 
Hemlock  in  Permanent  Construction. 


APPENDIX.  141 


EXTRACTS  FROM  TOPEKA  (KANSAS)   MELAN  ARCH   BRIDGE 

SPECIFICATIONS. 

By  permission  of  EDWIN  THACHER,  M.  Am.  Soc.  C.  E. 
PILING  IN   PERMANENT  WORK. 

Piling  and  lumber  for  coffer-dams  to  be  sound  white  oak,  yellow  pine,  or  other 
woods  equally  good  for  the  purpose,  the  quality  to  be  acceptable  to  the  superintendent. 
The  piles  shall  be  straight-grained,  trimmed  close,  and  have  all  bark  taken  off,  and 
shall  be  at  least  10  inches  in  diameter  at  the  small  end  and  14  inches  in  diameter  at  the 
butt  when  sawed  off.  The  heads  shall  be  cut  off  squarely  at  right  angles  to  the  axis 
of  the  pile,  and  all  piles  shall  be  fitted  to  and  driven  with  a  cast-iron  head.  The 
piles  shall  be  driven  with  a  hammer  weighing  not  less  than  two  thousand  two  hundred 
and  fifty  (2250)  pounds,  and  until  they  do  not  move  more  than  three-eighths (3/8)  of  an 
inch  under  a  blow  of  the  hammer  falling  twenty-five  (25)  feet.  No  pile  shall  be  driven 
less  than  twenty-six  (26)  feet  below  low  water,  and  if  necessary  to  attain  this  minimum 
depth  jets  shall  be  used  in  addition  to  hammer.  The  number  and  arrangement  of  the 
piles  for  each  foundation  are  shown  on  the  plans,  and  must  be  carefully  carried  out  by 
the  contractor.  The  piles  shall  be  cut  off  at  an  elevation  of  about  six  (6)  inches  below 
low  water.  A  slight  variation  will  be  allowed,  but  no  piles  must  be  cut  off  at  a  higher 
elevation.  Inspection  of  piling  and  lumber,  except  at  bridge  site,  shall  be  at  con- 
tractor's expense. 

COFFER-DAMS. 

After  the  bearing  piles  have  been  driven,  a  permanent  coffer-dam,  of  the  dimensions 
marked  on  the  plans,  of  Wakefield  (or  other  equally  satisfactory)  sheet  piling,  shall  be 
used  around  each  foundation.  The  earth  inside  thereof  shall  be  excavated  to  the 
depth  shown  on  plans  and  replaced  with  concrete  as  hereinafter  specified.  During  the 
placing  of  the  concrete  the  water  shall  be  kept  out  of  the  coffer-dams  unless  the  bottom 
is  so  porous  that  it  is  impracticable  in  the  opinion  of  the  superintendent  to  do  so — in 
which  case  some  of  the  concrete  may  be  placed  in  position  by  means  of  chutes  under 
the  direction  of  the  superintendent  until  the  bottom  is  well  calked,  after  which  the 
water  shall  be  pumped  out  and  the  remaining  concrete  placed  in  position.  The  con- 
tractor will  be  required  to  make  the  sides  and  ends  of  the  coffer-dams  water-tight,  and 
no  leak  through  them  will  be  considered  sufficient  cause  to  require  any  concrete  to  be 
placed  by  means  of  chutes. 

CENTERING. 

The  contractor  shall  build  an  unyielding  falsework,  or  centering,  of  the  form  and 
dimensions  shown  on  the  plans;  particular  care  must  be  taken  to  drive  the  piles  sup- 
porting it  to  a  solid  bearing.  The  estimated  load  upon  each  of  these  piles  is  twenty 
(20)  tons.  The  contractor  must,  however,  satisfy  himself  as  to  the  load  each  pile  will 
have  to  bear,  and  as  to  its  supporting  power.  In  case  of  any  settlement  the  contractor 
shall  take  down  and  rebuild  the  centering  and  arch.  The  lagging  shall  be  dressed  on 
both  edges  to  a  uniform  size  so  that  when  laid  it  will  present  a  smooth  surface,  and  this 
surface  shall  be  built  at  the  proper  elevation  to  allow  for  settlement  of  arch,  so  that 
when  the  centering  is  struck  the  arch  ring  will  come  to  the  elevations  shown  on  plans. 


142  APPENDIX. 

The  top  surface  of  the  lagging  shall  be  covered  with  W.  Field's  Building  Paper  of 
medium  weight,  known  as  Double  Saturated  Water-proof  Oiled  Sheathing  Paper  (or 
other  equally  good)  to  prevent  the  concrete  from  adhering  thereto,  No  center  shall 
be  struck  until  at  least  twenty-eight  (28)  days  after  the  completion  of  the  arch.  Great 
care  shall  be  used  in  lowering  the  centers  so  as  not  to  throw  undue  strains  upon  the 
arches,  nor  shall  any  center  be  struck  before  ihe  adjoining  arch  has  been  completed 
for  a  sufficiently  long  time,  in  the  opinion  of  the  superintendent,  to  be  uninjured 
thereby. 

NOTE.  —  For  the  above  reasons  it  is  probable  that  the  five  centers  will  be  in  use  at 
the  same  time. 

PORTLAND  CEMENT. 

The  Portland'cement  shall  be  a  true  Portland  cement,  made  by  calcining  a  proper 
mixture  of  calcareous  and  clayey  earths;  and  the  contractor  shall  furnish  one  or  more 
certified  statements  of  the  chemical  composition  of  the  cement  and  of  the  raw  materials 
from  which  it  is  manufactured.  Only  one  brand  of  Portland  cement  shall  be  used  on 
the  work,  except  with  permission  of  the  superintendent,  and  it  shall  in  no  case  contain 
more  than  two  (2)  per  cent  of  magnesia  in  any  form. 

The  fineness  of  the  cement  shall  be  such  that  at  least  98  per  cent  shall  pass  through 
a  standard  brass  cloth  sieve  of  74  meshes  per  linear  inch,  and  at  least  95  per  cent  shall 
pass  through  a  sieve  of  100  meshes  per  linear  inch. 

Samples  for  testing  may  be  taken  from  each  and  every  barrel  delivered  as  superin- 
tendent may  direct.  Tensile  tests  will  be  made  on  specimens  prepared  and  maintained, 
until  tested,  at  a  temperature  of  not  less  than  60  degrees  Fahrenheit.  Each  specimen 
shall  have  an  area  of  one  square  inch  at  the  breaking  section,  and  after  being  allowed 
to  harden  in  moist  air  for  twenty-four  hours  shall  be  immersed  and  retained  under 
water  until  tested. 

The  sand  used  in  preparing  the  test  specimensshall  be  clean,  sharp,  crushed  quartz, 
retained  on  a  sieve  of  30  meshes  per  linear  inch  and  passed  through  a  sieve  of  20  meshes 
per  linear  inch,  and  shall  be  furnished  by  contractor. 

No  more  than  23  to  27  per  cent  of  water  by  weight  Shall  be  used  in  preparing  the 
test  specimens  of  neat  cement,  and  in  making  the  test  specimens  one  of  cement  to  three 
of  sand,  no  more  than  II  or  12  per  cent  of  water  by  weight  shall  be  used. 

Specimens  prepared  from  neat  cement  shall  after  seven  days  develop  a  tensile 
strength  not  less  than  400  pounds  per  square  inch.  Specimens  prepared  from  a 
mixture  of  one  part  cement  and  three  parts  sand  (parts  by  weight)  shall  after  seven 
days  develop  a  tensile  strength  of  not  less  than  140  pounds  per  square  inch,  and  after 
twenty-eight  days  not  less  than  200  pounds  per  square  inch.  Specimens  prepared 
from  a  mixture  of  one  part  cement  and  three  parts  sand  (parts  by  weight)  and  immersed, 
after  twenty-four  hours,  in  water  to  be  maintained  at  176  degrees  Fahrenheit,  shall 
not  swell  nor  crack,,  and  shall  after  seven  days  develop  a  tensile  strength  of  not  less 
than  140  pounds  per  square  inch. 

Cement  mixed  neat  with  about  27  per  cent  of  water,  to  form  a  stiff  paste,  shall, 
after  30  minutes,  be  appreciably  indented  by  the  end  of  a  wire  one-twelfth  inch  in 
diameter,  loaded  to  weigh  one-quarter  pound. 

Cement  made  into  thin  cakes  on  glass  plates  shall  not  cr^ck,  scale,  or  \varp  under 
the  following  treatment:  three  pats  shall  be  made  and  allowed  to  harden  in  moist  air 
at  from  60  to  70  degrees  Fahrenheit;  one  of  these  shall  be  subjected  to  water  vapor  at 
176  degrees  Fahr.  for  three  hours,  after  which  it  shall  be  immersed  in  hot  water  for 
forty-eight  hours;  another  shall  be  placed  in  water  at  from  60  to  70  degrees  Fahrenheit, 
and  the  third  shall  be  left  in  moist  air. 

Samples  of  one-to-two  mortar  and  of  concrete  shall  be  made  and  tested  from  time 
to  time  as  directed  by  the  superintendent.  All  cement  shall  be  housed  and  kept  dry 
till  wanted  in  the  work. 

Storage  rooms  and  rooms  and  apparatus  for  the  tests  shall  be  furnished  by  the  con- 
tractor, and  all  tests  shall  be  made  entirely  at  his  expense,  and  under  the  direction  and 
to  the  satisfaction  of  the  superintendent. 


APPENDIX.  143 


PORTLAND  CEMENT  CONCRETE. 

The  concrete  shall  be  composed  of  clean,  hard,  broken  limestone  (or  gravel  with 
irregular  surfaces)  and  cement  mortar  in  volumes  as  hereinafter  described.  The  sand 
shall  be  clean,  sharp,  Kansas  River  sand,  washed  entirely  free  from  earth  and  loam. 
If  obtainable,  a  mixture  of  coarse  and  fine  sand  shall  be  used.  Approved  mixing 
machines  shall  be  used.  These  machines  must  be  kept  clean  and  no  accumulations  of 
old  mortar  shall  be  allowed  to  form  in  them.  The  ingredients  shall  be  placed  in  the 
machine  in  a  dry  state  and  in  the  volumes  specified  and  be  thoroughly  mixed,  after 
which  clean  water  shall  be  added  and  the  mixing  continued  until  the  wet  mixture  is 
thorough  and  the  mass  uniform.  No  more  wrater  shall  be  used  than  the  concrete  will 
bear  without  quaking  in  ramming.  The  mixing  must  be  done  as  rapidly  as  possible, 
and  the  batch  deposited  in  the  work  without  delay,  and  before  the  cement  begins  to  set. 
Stone  must  be  entirely  free  from  earth  and  earthy  surfaces.  Thin  splints  or  leaves  of 
stone,  easily  broken  with  fingers,  will  not  be  allowed  to  go  into  the  work.  The  quality 
of  stone  and  the  crushing  must  be  acceptable  to  the  superintendent. 

The  grades  of  concrete  to  be  used  are  as  follows  (parts  by  volume): 

For  the  arches:  one  part  Portland  cement,  two  parts  sand,  and  four  parts  broken 
stone  (hazelnut  size,  from  one-half  inch  to  one  inch),  except  for  the  exposed  faces  and 
soffits  of  the  arches,  which[shall  have  at  least  one  inch  in  thickness  of  mortar  composed 
of  one  part  Portland  cement  and  two  parts  sand. 

For  the  piers,  abutments,  spandrel  and  wing  walls:  on  the  exposed  surfaces  for  at 
least  one  inch  thick  one  part  Portland  cement  and  two  parts  sand;  for  the  next  seven 
(7)  inches  one  part  Portland  cement,  two  parts  sand,  and  four  parts  broken  stone  of 
hazelnut  size.  For  the  remaining  portions-  one  part  Portland  cement,  four  parts  sand, 
and  eight  parts  broken  stone  of  size  to  pass  through  a  three-inch  ring;  except  such  por- 
tions of  the  interior  of  the  piers  and  abutments  as  are  above  the  top  of  the  cornice,  or 
elevation  15.75  ft.  above  low  water,  which  shall  be  composed  of  one  part  Portland 
cement,  three  parts  sand,  and  six  parts  broken  stone  which  will  pass  through  a  two  and 
one-half  inch  ring. 

No  plastering  of  surfaces  will  be  allowed  nor  any  practice  that  will  develop  planes 
or  surfaces  of  demarkation  other  than  those  hereinafter  described.  Immediately  after 
the  removal  of  any  forms  or  centers,  sand  and  cement  shall  be  sifted  on  the  surfaces 
and  the  surfaces  rubbed  hard  with  a  float  as  may  be  directed  by  the  superintendent. 

During  warm  and  dry  weather  and  whenever  the  superintendent  shall  direct,  all 
newly  built  concrete  shall  be  kept  well  shaded  from  the  sun  and  well  sprinkled  with 
water  at  the  surface  for  several  days  or  until  well  set. 

There  must  be  no  definite  plane  or  surface  of  demarkation  between  the  facing  and 
the  concrete  backing.  The  facing  and  the  backing  must  be  deposited  in  the  same  layer 
and  well  rammed  in  place  at  the  same  time. 

In  connecting  old  concrete  with  new,  in  the  planes  hereafter  described,  the  old 
concrete  shall  be  cleaned  and  roughened  and  soaked  with  water,  and  at  the  points  of 
contact  a  mortar  composed  of  one  part  cement  and  two  parts  sand  shall  be  used  and 
shall  be  laid  in  the  same  manner  as  specified  for  laying  the  facing. 

NATURAL  CEMENT  CONCRETE. 

The  concrete  around  piles,  to  take  the  place  of  the  earth  excavated  from  the  coffer- 
dams, shall  be  composed  of  one  part  natural  cement,  equal  to  the  best  Fort  Scott,  Kas., 
cement,  three  parts  sand,  and  six  parts  of  broken  stone  of  the  size  to  pass  through  a 
three-inch  ring.  This  concrete  may  be  mixed  by  hand  on  platforms  adjoining  the 
foundations  and  shoveled  directly  into  the  coffer-dams,  care  being  taken  to  deposit  it 
in  uniform  layers  of  about  six  inches  each  and  to  carefully  ram  each  layer. 


144  APPENDIX. 


PIERS,  ABUTMENTS,  AND  SPANDRELS. 

All  piers,  abutments,  spandrels,  and  wing  walls  shall  be  built  in  timber  forms. 
These  forms  shall  be  substantial  and  unyielding,  of  proper  dimensions  for  the  work 
intended  and  closely  pointed,  and  all  surfaces  that  come  in  contact  with  the  concrete 
shall  be  smoothly  dressed  and  well  oiled  with  linseed  oil  to  prevent  the  concrete  from 
adhering  to  them.  That  portion  next  to  the  exposed  faces  of  the  work  need  not  be 
oiled,  but  shall  be  covered  with  oiled  paper,  the  same  as  that  specified  for  the  centers. 

Molds,  to  form  molding  and  panels,  smoothly  finished  and  well  oiled  with  linseed 
oil,  shall  be  properly  placed  in  the  forms  so  that  the  finished  work  will  appear  as 
shown  on  the  plans.  Extreme  care  must  be  used  to  place  them  in  proper  position 
before  placing  any  concrete  or  mortar  in  them. 

CONTINUOUS  WORK. 

The  following  divisions  shall  constitute  sections  for  continuous  work,  viz.:  each 
footing  course  of  piers  or  abutments  ;  each  pier  or  abutment  from  footing  course  to 
cornice  ;  each  pier  or  abutment  from  cornice  to  springing  line  of  arch  ;  each  spandrel 
wall  from  keystone  to  pier  or  abutment  ;  each  pier  or  abutment  spandrel  wall  ;  that 
portion  of  the  piers  or  abutments  above  springing  line  of  arch  shall  be  considered 
part  of  the  longitudinal  sections  of  the  arch  previously  described. 

Each  of  the  above  sections  shall  be  carried  on  continuously  night  and  day  if  nec- 
essary ;  that  is,  each  layer  shall  be  well  rammed  in  place  before  the  previously  de- 
posited layer  shall  have  time  to  partially  set. 

Care  shall  be  taken  to  make  the  joints  (for  expansion)  in  each  spandrel  wall  over 
piers  as  indicated  on  the  plans. 

CONCRETE  IN  COFFER-DAMS. 

The  natural  cement  concrete  in  the  coffer-dams  shall  extend  from  depths  marked 
on  plans  to  one  foot  below  low  water.  Upon  this  concrete  the  footing  courses  of  piers 
and  abutments  shall  be  founded. 

The  sheet  piling  of  coffer-dams  shall  be  cut  off  at  least  down  to  low-water  mark, 
neatly  and  evenly,  by  the  contractor  before  the  completion  of  the  work. 


APPENDIX.  H5 


EXTRACTS    FROM    KATTE'S   MASONRY   SPECIFICATIONS. 

By  permission  of  WALTER  KATTE,  M.  Am.  Soc.  C.  E. 

EXCAVATIONS  will  be  classified  under  the  following  heads,  viz.:  earth,  hardpan, 
loose  rock,  solid  rock,  and  excavation  in  water. 

EARTH  will  include  clay,  sand,  gravel,  loam,  decomposed  rock  and  slate,  stones 
and  boulders  containing  less  than  one  cubic  foot,  and  all  other  matters  of  an  earthy 
nature,  however  compact,  excepting  only  "  hardpan,"  as  described  below. 

HARDPAN  will  consist  of  tough,  indurated  clay  or  cemented  gravel  which,  in  the 
opinion  of  the  Engineer,  requires  blasting  for  its  removal. 

LOOSE  ROCK. — All  boulders  and  detached  masses  of  rock  measuring  over  one  (i') 
cubic  foot  in  bulk,  and  less  than  one  (i)  cubic  yard  ;  also  all  slate,  shale,  soft  friable 
sandstone  and  soapstone,  and  all  other  materials  excepting  rock,  solid  ledge,  and 
those  described  above  ;  also  stratified  rock  in  layers  of  not  exceeding  eight  (8")  inches 
in  thickness,  when  separated  by  strata  of  clay,  and  which,  in-  the  judgment  of  the 
Engineer,  may  be  removed  without  blasting,  although  blasting  may  occasionally  be 
resorted  to. 

SOLID  ROCK  will  include  all  rock  found  in  ledges,  or  masses  of  more  than  one  (i) 
cubic  yard,  which,  in  the  judgment  of  the  Engineer,  may  be  best  removed  by  blasting  , 
with  the  exception  of  stratified  rocks  described  under  the  head  of  Loose  Rock.  In  rock 
excavations  the  "  bottom  "  must  in  all  cases  be  taken  down  truly  to  sub-grade  ;  and 
when  so  ordered  by  the  Engineer  ditches  must  be  formed  at  the  foot  of  the  slope. 

The  contract  price  for  excavation  will  apply  to  pits  required  for  foundations  of 
masonry  when  water  is  not  encountered,  and  the  price  for 

EXCAVATION  IN  WATER  will  only  apply  to  foundation  pits  under  water  and  deep- 
ening of  channels  in  running  water  ;  it  must  cover  all  classes  of  material,  and  include 
drainage,  bailing,  pumping,  and  all  materials  and  labor  connected  with  such  excava- 
tions ;  also  the  necessary  dressing  of  the  rock. 

CEMENT  must  be  of  the  best  quality  of  freshly  burned  and  ground  hydraulic 
cement,  and  be  equal  in  quality  to  the  best  brands  of  Cement.  It 

will  be  subject  to  test  made  by  the  Engineer  or  his  appointed  inspector,  and  must 
stand  a  proof  tensile  test  of  fifty  (50)  pounds  per  square  inch  of  sectional  area  on 
specimens  allowed  a  set  of  thirty  (30)  minutes  in  air  and  twenty-four  (24;  hours  under 
water. 

MORTAR  will  in  all  cases  be  made  of  one  part  in  bulk  of  the  best  hydraulic  cement 
to  two  parts  in  bulk  of  clean,  sharp  sand,  well  and  thoroughly  mixed  together  in  a 
clean  box  of  boards,  before  the  addition  of  the  water,  and  must  be  used  immediately 
after  being  mixed.  No  mortar  left  over  night  will,  under  any  pretext,  be  allowed  to 
be  used.  The  sand  and  cement  used  will  at  all  times  be  subject  to  inspection,  test, 
acceptance,  or  rejection  by  the  Engineer. 

CONCRETE. — Concrete  shall  be  composed  of  fragments  of  hard,  sound,  and  accept- 
able stone,  broken  to  a  size  that  will  pass  through  a  two  (2")  inch  ring  in  any  direction, 
thoroughly  clean  and  free  from  mud,  dust,  dirt,  or  any  earthy  admixture  whatever  ; 
mixed  in  the  proportion  of  two  (2)  parts  in  bulk  of  the  broken  stone  to  one  (i)  part  of 
fresh-made  cement  mortar  of  the  quality  herein  described  ;  and  is  to  be  quickly  laid  in 
sections  and  in  layers  not  exceeding  nine  (9)  inches  in  thickness,  and  to  be  thoroughly 
rammed  until  the  mortar  Hushes  to  the  surface  ;  it  shall  be  allowed  at  least  twelve  (12) 
hours  to  "  set"  before  any  work  is  laid  on  it. 


APPENDIX. 


FOUNDATIONS. 

GENERAL  DESCRIPTION.  —  Foundations  for  masonry  shall  be  excavated  to  such 
depths  as  may  be  necessary  to  secure  a  solid  bearing  for  the  masonry,  of  which  the 
Engineer  shall  be  the  judge.  The  materials  excavated  will  be  classified  and  paid  for. 
as  provided  for  in  these  specifications,  under  the  general  head  of  Excavations  ;  and  in 
case  of  foundations  in  rock,  the  rock  must  be  excavated  to  such  depth  and  in  such 
form  as  may  be  required  by  the  Engineer,  and  must  be  dressed  level  to  receive  the 
foundation  course. 

When  a  safe  and  solid  foundation  for  masonry  cannot  be  found  at  a  reasonable  depth 
(to  be  judged  of  by  the  Engineer),  there  will  be  prepared  by  the  contractor  such  artifi- 
cial foundations  as  the  Engineer  may  direct.  All  materials  taken  from  the  excavations 
for  foundations,  if  of  proper  quality,  shall  be  deposited  in  the  contiguous  embankment; 
but  any  material  unfit  for  such  purpose  shall  be  deposited  outside  the  roadway,  or  in 
such  place  as  the  Engineer  shall  direct,  and  so  that  it  shall  not  interfere  with  any 
drain  or  watercourse. 

TIMBER.— Timber  foundations  when  required  shall  be  such  as  the  Engineer  may  by 
drawings  or  otherwise  prescribe,  and  will  be  paid  for  by  the  one  thousand  feet,  board 
measure.  The  price,  covering  cost  of  material,  framing  and  putting  in  place,  and  all 
wrought- and  cast-iron  work  ordered  by  the  Engineer,  will  be  paid  for  per  pound,  the 
price  including  cost  of  material,  manufacture,  and  placing  in  the  work. 

PILING. — All  timber  used  in  foundations  or  foundation  piling  shall  be  of  young, 
sound,  and  thrifty  white  oak,  yellow  pine,  or  other  timber  equally  good  for  the  purpose, 
acceptable  to  the  Engineer.  Piles  must  be  at  least  eight  (8")  inches  in  diameter  at  the 
small  end  and  twelve  (12")  inches  in  diameter  at  the  butt  when  sawn  off;  they  must  be 
perfectly  straight  and  be  trimmed  close,  and  have  the  bark  stripped  off  before  they  are 
driven.  They  must  be  driven  into  hard  bottom  until  they  do  not  move  more  than  one- 
half  inch  under  the  blow  of  a  hammer  weighing  two  thousand  (2000)  pounds,  falling 
twenty-five  (25')  feet  at  the  last  blow.  They  must  be  driven  vertically  and  at  the  regular 
distances  apart  from  centers,  transversely  and  longitudinally,  as  required  by  the  plans 
or  directions  of  the  Engineer;  they  must  be  cut  off  squarely  at  the  butt  and  be  well 
sharpened  to  a  point,  and  when  necessary,  in  the  opinion  of  the  Engineer,  shall  be  shod 
with  iron  and  the  heads  bound  with  iron  hoops,  of  such  dimensions  as  he  may  direct, 
which  will  be  paid  for  the  same  as  other  iron  work  used  in  foundations. 

The  necessary  length  of  piles  shall  be  ascertained  by  driving  test  piles  in  different 
parts  of  the  localities  in  which  they  are  to  be  used;  and  in  case  a  pile  shall  not  prove 
long  enough  to  reach  "  hard  bottom  "  it  shall  be  sawed  off  square,  and  a  hole  two  (2") 
inches  in  diameter  be  bored  into  its  head  twelve  (12")  inches  deep;  into  this  hole  a 
circular  white-oak  trenail  twenty  three  (23")  inches  in  length  shall  be  well  driven,  and 
another  pile  similarly  squared  and  bored,  and  of  as  large  a  diameter  at  the  small  end 
as  can  be  procured,  shall  be  placed  upon  the  lower  pile,  brought  to  its  proper  position, 
and  driven  as  before  directed.  •  All  piles,  when  thus  driven  to  the  required  depth,  are  to 
be  cut  off  truly  square  and  horizontal  at  the  proper  height  given  by  the  Engineer,  and 
only  the  actual  number  of  lineal  feet  of  the  piles  left  for  use  in  the  foundations  after 
being  sawn  off  will  be  paid  for. 

COFFER-DAMS. — Where  coffer-dams  are,  in  the  opinion  of  the  Engineer,  required  for 
foundations  the  prices  provided  in  the  contract  for  timber,  piles,  and  iron  in  founda- 
tions will  be  allowed  for  the  material  and  work  on  same,  which  is  understood  as  cover- 
ing all  risks  from  high  water  or  otherwise,  draining,  bailing,  pumping,  and  all  materials 
connected  with  the  coffer-dams.  Sheet  piling  will  be  classed  as  plank  in  foundations, 
and  will  be  paid  for  per  one  thousand  (1000')  feet  board  measure  if  left  in  the  ground. 

TIMBER. 

All  timber  must  be  sound,  straight-grained,  and  free  from  sap,  loose  or  rotten  knots, 
wind  shakes,  or  any  other  defect  that  would  impair  its  strength  or  durability;  it  must 
be  sawed  (or  hewed)  perfectly  straight  and  to  exact  dimensions,  with  full  corners  and 
square  edges;  all  framing  must  be  done  in  a  thoroughly  workmanlike  manner,  and 
both  material  and  workmanship  will  be  subject  to  the  inspection  and  acceptance  of  the 
Engineer. 


APPENDIX.  147 


SPECIFICATIONS  FOR  STEEL  COFFER-DAM. 

DESIGN.  —  The  shell  shall  be  made  of  elliptical  shape  for  ordinary  piers  and  circular 
for  pivot  piers.  It  shall  be  made  not  less  than  four  feet  larger  than  footing  of  pier 
in  plan,  to  allo;v  for  variation  in  position  during  sinking. 

The  plates  used  shall  be  as  large  as  can  be  handled  with  ease  in  the  shop,  during 
shipment,  and  during  erection. 

The  splices  may  be  either  lap  or  butt  joints,  provided  a  good  tight  job  will  result, 
and  the  rivets  must  be  spaced  according  to  bcilermaker's  rules. 

The  joint  may  be  made  tight  by  calking  or  by  the  use  of  a  calking  strip,  but  in 
either  event  the  result  must  be  guaranteed. 

The  shell  must  be  stiffened  by  horizontal  stiffening  angles,  girders,  or  trussing,  to 
resist  deformation  during  the  placing  and  to  resist  both  the  quiescent  and  a  maximum 
unbalanced  earth  or  water  pressure,  or  a  wind  pressure. 

The  bottom  plates  shall  be  re-enforced  with  narrow  plates  inside  and  outside,  to 
form  a  wedge-shaped  cutting  edge;  and  when  there  is  rock  or  hard  bottom  the  plates 
shall  be  cut  to  conform  to  its  contour  as  nearly  as  possible. 

The  top  shall  be  properly  stiffened,  and  if  necessary  provided  with  connection  holes 
for  additional  sections. 

The  factor  for  safety  shall  in  no  case  be  less  than  four,  and  in  case  the  shell  will  be 
subject  to  shock,  not  less  than  six. 

No  metal  of  a  less  thickness  than  1/4  inch  shall  be  used  for  temporary  work,  nor  less 
than  3/8  inch  for  permanent  work  in  fresh  water  or  1/2  inch  in  salt  water. 

MATERIAL. — The  entire  shell  shall  be  constructed  of  the  grade  of  steel  known  as 
soft  medium,  except  rivets,  which  shall  be  of  bridge  quality  of  iron. 

The  steel  may  be  made  either  by  the  Bessemer  or  open-hearth  process,  and  the 
phosphorus  shall  never  exceed  0.08  per  cent. 

Soft  medium  steel  shall  have  an  ultimate  strength  of  from  55,000  1065,000  pounds 
per  square  inch,  as  determined  from  standard  rest  pieces  ;  an  elastic  limit  of  not  less 
than  one-half  the  ultimate  strength  ;  an  elongation  of  not  less  than  25  per  cent  in  8 
inches  ,  and  a  reduction  of  area  at  fracture  of  not  less  than  50  per  cent. 

Samples  to  bend  cold  180  degrees  to  a  diameter  equal  to  the  thickness  of  the 
sample,  without  crack  or  flaw  on  the  outside  of  the  bent  portion. 

ERECTION. — The  erection  must  be  done  in  a  first-class  manner,  and  all  rivets  must 
have  full  heads.  The  shell  shall  be  placed  in  position  within  one-half  the  distance 
allowed  for  error  in  the  design  of  the  coffer-dam.  Only  a  reasonable  variation  will  be 
allowed  for  difference  in  level. 

PAINTING. — All  the  metal  work  shall  be  thoroughly  cleaned  of  rust  or  scale  at  the 
shops  and  coated  thoroughly  with  hot  asphaltum. 

Before  erection,  in  the  field,  it  shall  be  given  a  second  coating  of  hot  asphaltum. 

SEALING. — When  in  position  on  the  bottom,  if  the  coffer-dam  has  not  been  sunk 
through  impervious  strata,  it  shall  be  sealed  by  concreting  around  the  circumference 
inside  with  concrete  passed  through  a  tube. 

REMOVAL. — Should  the  coffer-dam  not  form  a  part  of  the  permanent  foundation 
it  shall  be  taken  apart,  at  the  joints  designed  for  ihe  purpose,  and  carefully  removed 
in  such  a  manner  as  not  to  injure  the  foundation,  and  so  as  to  be  used  again  if  required. 


I4§  APPENDIX. 

HEALD   &   SISCO   STANDARD    IRON   HORIZONTAL   CENTRIFUGAL  PUMPS, 


Horse-power 

No. 

Capacity  in 
Gallons  per 
Minute. 

required  for 
Each  Foot 
of  Lift. 
Minimum 

Diameter 
and  Face 
of  Pulley 
in  Inches. 

Floor 
Space 
required, 
in  Inches. 

Shipping- 
Weight. 
Pounds. 

Price  of 
Pump, 
Oilers  and 
Wrench. 

Price  of 
Pump  and 
Primer. 

No. 

Quantity. 

It 

50  to          70 

.024 

6X6 

17  X     30 

168 

$45 

$55 

I* 

If 

75  to       100 

•037 

7X8 

21  X    33 

232 

60 

70 

If 

2 

no  to      150 

•054 

8  X     8 

23  X    37 

306 

75 

90 

2 

2| 

175  to      250 

.086 

8X8 

24  X    38 

348 

90 

105 

at 

3 

250  to      350 

.124 

8X8 

25  X    39 

400 

no 

130 

3 

4 

450  to      600 

.223 

10  X  10 

30  X    40 

545 

130 

155 

4 

5 

750  to      900 

•372 

15    X    12 

34  X     54 

826 

165 

195 

5 

6 

1000  to     1400 

.496 

15  X  12 

37  X    55 

965 

200 

240 

6 

8 

I7OO  to      22OO 

.844 

2O   X    T2 

45  X    63 

1500 

310 

375 

8 

10 

22OO  to      3OOO 

1.093 

24   X    12 

5i  X    71 

2170 

395 

470 

10 

12 

3000  to    4000 

1.49 

30  X  14 

62  X    78 

3050 

500 

12 

15 

4800  to     6000 

2.38 

40  X  15 

77  X    So 

7100 

850 

15 

•is 

4800  to    6000 

2.38 

30  x  15 

60  X    68 

3150 

710 

15 

18 

7500  to  loooo 

3-73 

40  X  15 

93  X  103 

9000 

1300 

18 

*i8 

7500  to  10000 

3-73 

30  X  16 

62  X    70 

3500 

1150 

18 

22 

I2OOO  tO   I4OOO 

5-96 

48  X  20 

126  X  130 

12000 

22 

*  Refers  to  low-lift  pump. 

The  number  of  pump  is  also  diameter  of  discharge  opening  in  inches.  Where  more 
than  25  feet  of  discharge  pipe  is  attached  to  pump,  use  one  or  two  sizes  larger  than 
pump  discharge. 

For  No.  12  and  larger  sizes  a  foot  valve  or  flap  valve  and  ejector  for  priming  is 
recommended. 


LIST    OF    HEALD    &    SISCO    HYDRAULIC    DREDGING    AND    SAND    PUMPS. 


Num- 
ber of 
Pump. 

Diameter 
Suction 
and  Dis- 
charge 
Open- 
ings. 

Cubic 
Yards  of 
Material 
they  will 
Raise  per 

Hour 

Horse- 
power 
recom- 
mended 
for  10- 
Foot 

Diameter 
and  Face 
of  Pulley. 

Floor  Space 
Required. 
Inches, 

Shipping 
Weight. 
Pounds. 

Will 
Pass 
Solids, 
Diameter. 
Inches 

Price  of  Pump 
Complete,  with 
Suction  and 
Discharge 
Elbows,  Flap 
Valve  and 

Num- 
ber 
of 
Pump. 

Inches. 

Lift. 

Ejector. 

4 

4 

30  to     50 

6 

12  X  12 

40  x  31 

800 

2 

$2IO 

4 

6 

6 

60  to    80 

12 

20  X  12 

68  X  40 

I7OO 

4i 

3OO 

6 

8 

8 

125  to  150 

22 

24  X  14 

72  x  48 

3400 

6 

475 

8 

10 

10 

2OO  tO   3OO 

35 

30  x  15 

94  X  54 

4200 

8 

600 

10 

12 

12 

300  to  375 

45 

36  X  20 

114  X  66 

9OOO 

10 

850 

12 

15 

15 

400  to  500 

75 

42  X  24 

154  X  78 

I2OOO 

10 

1450 

15 

18 
20 

18 
2O 

500  to  700 

125 

48  X  30 

160  X  80 

13500 

IO 

1900 

18 
20 

22 

22 

.... 

22 

APPENDIX. 


149 


NUMBER  OF  REVOLUTIONS  AT   WHICH    PUMPS  SHOULD   RUN   TO   RAISE 
WATER    TO    DIFFERENT    HEIGHTS. 


No. 

5  Feet. 

10  Feet. 

15  Feet. 

20  Feet. 

25  Feet. 

30  Feet. 

35  Feet. 

40  Feet. 

I* 

428 

604 

739 

854 

955 

1045 

H3I 

1208 

If 

348 

491 

60  1 

695 

777 

850 

920 

982 

2 

3O2 

426 

522 

603 

674 

737 

798 

852 

2* 

302 

426 

522 

603 

674 

737 

798 

852 

3 

302 

426 

522 

603 

674 

737 

798 

852 

4 

285 

402 

493 

569 

637 

697 

754 

805 

5 

256 

362 

443 

512 

572 

626 

678 

724 

6 

214 

302 

368 

427 

478 

523 

566 

604 

8 

183 

259 

317 

366 

409 

448 

485 

517 

10 

168 

238 

291 

336 

376 

411 

445 

475 

12 

133 

188 

230 

266 

298 

326 

352 

376 

15 

105 

148 

181 

2OQ 

234 

256 

277 

295 

*I5 

151 

213 

261 

301 

337 

369 

399 

426 

18 

105 

148 

181 

209 

234 

256 

277 

295 

*iS 

151 

213 

261 

301 

337 

369 

399 

426 

*  Refers  to  low^lift  pumps. 

Above  table  gives  correct  speed  of  pumps  as  employed  under  usual  conditions  of 
pumping.  If  water  must  be  forced  through  a  number  of  bends  and  elbows,  or  a  great 
length  of  piping,  the  above  speed  must  be  somewhat  increased. 

Use  large  pipes  and  easy  bends  wherever  practicable,  as  they  save  power. 


TABLE    OF    SIZES,    LIDGERWOOD    SINGLE-CYLINDER,   SINGLE-DRUM 

HOISTING-ENGINES. 


•d 
u 

Dimensions  of 
Cylinder. 

3 
w    <u   «i 

ij-* 

Dimensions  of 
Hoisting-drum. 

Dimensions  of 
Bed-plate. 

Dimensions  of  Boiler 

'E.-^ 

•-  o\J 

'v      c 

>, 

>> 

_• 

f.% 

0^ 

B 

X 

Diameter. 
Inches. 

.  ti 

ji-g 

2JS 

p 

11 

Diam  Bod 
between 
Flanges. 
Inches. 

So^jS  <•> 

Q 

Width. 
Inches. 

tl 

Diameter 
Shell. 
Inches. 

Height  She 
Inches. 

Number  of 
2-inch 
Tubes. 

Estimated 
Weight  C 
Lbs 

4 

5 

8 

I2OO 

1000 

,0 

20 

22 

38 

60 

28 

63 

40 

3550 

6 

63- 

8 

I5OO 

1250 

10 

20 

22             38 

60 

28 

69 

40 

3950 

8 

6|- 

IO 

1750 

1500!       12 

20 

24             41 

73 

30 

72 

44 

4850 

IO 

7 

10 

2500 

i8oo!     12 

2O 

24             41 

73 

32 

75 

48 

5050 

n 

7 

10 

2500 

2000        14 

22 

26 

45 

73 

34 

78 

52 

5350 

12} 

81 

IO 

4000 

2500;       14 

23 

29 

47 

73 

36 

75 

57 

6550 

15 

IO 

4OOO 

28OO        14 

23 

29 

47 

73 

36 

81 

57 

6750 

20 

8* 

12 

6OOO 

4000      1  6 

26 

33          54 

84 

40 

84 

80 

8500 

25 

IO 

12 

8000 

5000!      16 

26 

33 

54 

84 

42 

90 

88 

9500 

ISO 


APPENDIX. 


TABLE    OF    SIZES,    LIDGERWOOD    DOUBLE-CYLINDER,    DOUBLE-DRUM 

HOISTING-ENGINES. 


•a 
aj 

Dimensions  of 
Cylinders. 

Dimensions  of 
Hoisting-drums 

1«1 

w  be 
•tf|* 

Dimensions  of  Boiler. 

Dimensions  of 
Bed-plate. 

.9- 

£^  u 

£& 

o  o(/> 

£]?=« 

g£ 

~  <u  ** 

ujk  g^ 

Num- 

U>  0  £ 

§rt         a 

£3 

Diam. 

Stroke. 

Diam. 

Length. 

"bVbflw 

"re^1  B.y 

Diam. 

Height. 

ber  of 

Width. 

Length 

E    CO 

Inches. 

Inches. 

Inches. 

Inches. 

•jj  £  > 

•-<<-i  »2  .2 

Inches. 

Inches. 

2-inch 

Inches. 

Inches. 

ED 

jgj</3< 

(/} 

Tubes. 

«a*U 

8 

5 

8 

12 

22 

2OOO 

1500 

32 

75 

48 

47 

80 

650-) 

12 

6} 

8 

14 

22 

3OOO 

2000 

36 

75 

57 

50 

86 

8OOO 

16 

10 

14 

26 

4OOO 

2800 

38 

81 

68 

54 

89 

9000 

20 

7 

10 

14 

26 

5000 

3500 

40 

84 

80 

54 

89 

9550 

30 

H 

IO 

14 

27 

8000 

5OOO 

42 

90 

88 

57 

94 

II400 

40 

81 

12 

16 

32 

IOOOO 

8000 

50 

IO2 

124 

70 

117 

2IOOO 

50 

10 

12 

16 

32 

I2OOO 

IOOOO 

53 

IO2 

150 

70 

117 

22000 

INDEX. 


Aa  river,  Russia,  83 
Ancient  methods  of — 

Founding,  I,  3,  4,  5 

Pile  driving,  5,  40,  41 

Pumping,  92,  93 

Sheet  piling,  6,  7 

Anchoring,  coffer-dam,  30,  32,  33,  87 
Approval,  War  Dep't,  120 
Arkansas  river,  20,  70 
Architectural  design,  piers,  125,  127,  131 
Arch  bridge — 

Center,  141 

Hutcheson,  Scotland,  6 

Largest,  3 

Melan,  Topeka,  78,  119,  141,  142 

Roman,  I 

Shuster,  Persia,  I 

Topeka,  Kansas,  78,  119,  141,  142 

Trezzo,  I 

Asphalt  for  leaks,  65 
Bamboo  casings,  4 
Bank  protection — 

Japanese,  4 

Mississippi,  4 
Bascule  pump,  92 
Batter  of  piers,  125 
Bear  river,  Canada,  83 
Bearing — 

Piles,  106.  146 

Power  of  piles.  49 
Blasting,  33,  73,  89 
Boiler  riveting,  80,  82,  147 
Bolts,  7,  57,  139 

See  Drift-bolts 
Borings — 

Auger,  Pierce,  121 

Casing  for,  121 

Clamp  for  driving  tube,  122 

Core  removal,  122 

Cutting  shoe  for  pipe,  122 

Drills  foi ,  121 

Driving  pipe  for,  122 

Extensive,  121 

Hand  drills  for,  121 

Jars  for,  121 

Maul  for  driving  pipe,  122 


Borings — Continued. 

Obstructions  to,  121 

Pebble-tongs,  124 

Pump,  sand,  121,  122 

Removal  of  core,  122 

Rope  knives,  121 

Rope  spears,  121 

Sand  pump,  121,  122 

Screw,  adjusting,  121 

Spears,  rope,  121 

Temper  screw,  121 

Test,  121 

Tongs,  pebble,  124 

Tripod  for,  121 

Well-driller,  121 
Bottom — 

Clay,  38,  57,  60,  73,  77 

Drift  in  sand,  18 

Gravel,  6,  16,  20,  57,60,  64,  66,  74,  106,  133 

Hard  clay,  10,  12,  77,  106 

Mud,  17,  38,  60,  62,  77,  106 

Open  (porous),  16,  28 

Overlaid.      See  Rock 

Porous,  16,  28,  141 

Quicksand,  67 

Rock,   i,  20,  24,  25,  26,  28,  29.  30,  32,  33, 
36,  38,  39,  57,  62,  66,  72,  74,  77.  86,  106 

Rock,  overlaid,  16,  20,  24    25,  29,  33,  36, 
38,  57,  66,  72,  74,  77,  106 

Sand,  62,  64,  68,  77,  78,  106 

Sand  and  drift,  18 

Sand  and  shells,  77 

Shale,  60 

Shells  in  sand,  77 

Silt,  33 

Soapstone,  20 

Soundings,  86,  120,  121 

Uneven,  17,  32,  33,  36,  62,  76,  106 
Boxing  in  leaks,  32,  39,  60 
Box  pump,  93 

Bras  d'Or  river,  Canada,  82 
Brace  rods,  30,  38,  67,  134 
Braces,  7,  30,  33,  38,  39,  56,  64,  67,   76    80, 

83,  84,  135 

Bridge  location,  120 
Bridge  cost,  economic,  124,  125 


152 


INDEX. 


Bridges  referred  to — 

Ann  Arbor,  59 

Arnprior,  18 

Arthur  Kill,  38,  60 

Baltimore,  N.  Ave.,  118 

Blackfriars,  London,  4 

Boucicault    France,  109 

Buda-Pesth,  8,  28,  50,  53 

Caesar's,  over  Rhine,  5,  40 

Charlestown,  Boston,  53,  63 

Chattanooga,  Walnut  St.,  66,  99,  107 

Coteau,  39 

Cumberland,  Md.,  67 

Fair  Haven,  48 

Forth,  Scotland,  86,  99,  107 

Fort  Madison,  la.,  20 

Gadsden,  Ala.,  74 

Harvard,  Boston,  no 

Harlem  ship-canal,  36 

Harper's  Ferry,  63 

Hawkesbury,  Australia,  80 

Hutcheson,  Glasgow,  6,  50,  57 

Little  Rock,  Ark.,  70,  in 

Melbourne,  Australia,  33 

Momence,  Illinois,  62 

Neuilly,  France,  92 

Omaha,  Nebraska,  127 

Orleans,  France,  40,  92,  93 

Philadelphia,  Walnut  St.,  24 

Phila.  &  Reading  R.  R.,  74 

Putney,  England,  77 

Red  River,  in 

Riga-Orel,  Russia,  83 

Rochester,  Court  St.,  117 

Saumur,  France,  41 

Shuster,  Persia,  i 

Topeka,  Kansas,  78,  119 

Trajan's,  40 

Tulsa,  20 

Victoria,  Canada,  83 

Westminster,  London,  4 
Bucket-wheel  pump,  92 
Bucket  for  concrete,  36,  39,  no 
Bull-wheel  pile  driver,  41 
Bulkhead,  30 
Cableway — 

Capacity  of,  117 

Carriage  for,  117 

Span  of,  117,  118 

Use  of,  117 
Caisson — 

Open,  3,  4,  13 

Pneumatic,  5 

Water-tight,  74 
Calking — 

Cylinders,  82 

Joints,  20,  36,  147 
Canal— 

Chicago  drainage,  117" 

Harlem  ship,  36 

Illinois  &  Miss..  113 

Keokuk,  la.,  30 

N.  Y.  State,  45,  50 


Candle  wick  for  leaks,  20 
Cane  stalks  for  leaks,  28 
Canvas  sheet,  30,  31,  32,  33,  35 
Capacity  of — 

Cableway,  117 

Dredge,  101,  102,  103,  135,  148 

Pumps,  77,  78,  93,  94,  99,  101,  135,  148 
Carriage  for  cableway,  117 
Casing — 

Bamboo,  4 

Boring,  121 

Timber,  5 
Cement  (see  Concrete) — 

Defective,  114,  136 

Laitance  of,  109 

Mortar,  136,  143,  145 

Natural,  in,  136,  143,  145 

Portland,  113,  115,  116,  142 

Quality  of,  114,  136,  142,  145 

Specifications,  136,  142,  145 

Tests  of,  115,  136.  142,  145 
Center  for  arch,  141 
Centrifugal  pump,  see  Pump 
Chamber,  width  of,  56 
Chamber,  see  puddle 
Changes,  139 
Channel— ' 

Establishing  new,  3 

Fixed  place  for,  120 

Requirements  of  Gov't,  120 
Chapelet  pump.  92,  93 
Charles  river,  Boston,  63,  no 
Circular — 

Coffer-dam,  see  Coffer-dam 

Pier  of  granite,  86 

Shell  for  pier,  see  cylinder 
Clam-shell  dredge,  102 
Clamp  for — 

Coffer-dam,  38 

Pile-driver,  43 

Pipe,  122 

Sheet  piles,  57 

Classification  of  excavation,  135,  145 
Clay,  see  Bottom 
Clay  puddle,  see  Puddle 
Clearance  in  coffer-dam,  74,  147 
Clyde  river,  Scotland,  6 
Coffer-dam — 

Anchoring,  30,  32,  33,  37 

Calculation  of,  54,  56,  84 

Canvas  and  plank,  30,  32,  33,  35 

Circular,  20,  24,  87,  147 

Clearance  in,  74.  147 

Cost  of,  61,  76,  77 

Crib  type,   14,  15,  17,  18,  20,  26,   32,   33, 
36.  38,  39,  72 

Damaged,  24,  32,  35,  60,  66,  76 

Decking  for,  134 

Definition  of,  13 

Deposit  in,  134 

Earth  bank  type,  5,  13,  14,  26 

Economy  in,  26 

Erecting  steel,  147 


Of  THK  ' 

UNIVERSITY 


INDEX. 


153 


Coffer-dam — Continued. 

Failure  of,  16,  24,  28,  30,  32,  60 

Floating  type,  74 

Frame  for,  30,  35,  59,  66,  67,  75 

Grillage  type,  20,  24 

Half-tide,  89 

Largest  recorded,  8 

Location  of,  86,  87 

Metal,  type  of,  83,  86,  147 

Movable,  20,  33,  74,  75, -76 

Moving,  time  required,  76 

Origin  of,  3,  5 

Pivot  pier,  20,  36,  38,  39,  147 

Polygonal  type,  36,  38,  39 

Price  for,  139 

Protection,  26,  33 

Puddle,  pressure  on,  54 

Puddle  for,  see  Puddle 

Removal  of,  120,  33,  74,  134,  147 

Removing  piers  by,  72,  74 

Robinson,  circular,  24 

Sheet  pile  type,  6,  8,  9,  24,  26,  59,  60,  61, 
62,  63,  64,  65,  134 

Sinking  with  stone,  20,  76 

Specifications  for,  6,  134,  141,  146,  147 

Splicing  in  height,  67,  147 

Tarpaulin  and  plank,  30,  32,  33,  35 

Tidewater  type,  8,  53,  63,  86 

Wakefield  piling,   14,   20,   53,   61,  62,  63, 
64,  141 

Water  pressure  on,  54,  56 

Width  of  chambers,  56 
Compartments,  water-tight,  76 
Completion  of  work,  139 
Composition  of  concrete,  see  Concrete 
Compound  sheet  piles,  52,  53,  61,  66 
Concrete — 

Ancient  use  of,  2,  4 

Bucket  for  depositing,  36,  39,  no 

Composition  of,  107,   no,  in,   116,  138, 

143,  M5 
Cost  of,  117 

Depositing,  rate  of,  115 
Facing  for,  72,  in,  114,  143 
Forms  for,  in,  113,  115,  141,  142,  144 
Foundation  of,   18,  24,  36,  60,  61,  63,  67, 

72,   107,   108,   116,    117,    138,   143,    144, 

146 

Laitance,  109 

Laying,  rules  for,  113,  138,  143,  145 
Layers,   proper  thickness,  109,  113,  138, 

143,  144,  145 

Leveling  course,  107,  117 
Louisville  cement  used,  ill 
Monolithic  construction,  72,  in,  112,  113, 

143 

Oil  paper  on  forms,  142 
Piers  of,  72,  in,  143,  144 
Pier  filling,  80,  82,  143 
Portland  cement  used,  72,  113,  115,  116, 

143 

Proportions  of,  67,  72,  107,  no,  in,  116, 
138,  143,  145 


Concrete — Continued. 
Puddle  of,  38.  78,  87 
Rate  of  deposit,  115,  143,  144,  145 
Rules  for  laying,   113,  138,  143,  144,  145 
Sacked  for  placing,  107 
Sand  for,  in,  115,  136,  143,  145 
Setting  time,  no,  114,  143,  144,  145 
Stone  for,  in,  115,  143,  145 
Tube  for  depositing,  108,  no 
Under  water,  36,  39,  107,  108,  109,  no,  142 
Water,  amount  for,  113,  114,  143 
Wells  in.  114 

Coosa  river,  Ala.,  74,  no,  117 
Coping,  125,  127,  129,  137 
Corbel  course,  127,  129 
Core  removal,  test,  122 
Corporation,  applicant  for  bridge,  120 
Cost  of — 

Bridge,  least,  124 
Coffer-dam,  61,  76,  77 
Concrete,  117 
Dredgers,  103 
Dredging,  103,  148 
Driving  piles,  48 
Formula  for,  spans,  124 
bridge,  124 
piers,  125 

Hoist-engines,  44,  45 
Piers,  125 
Pumps,  93,  148 
Removing  pier,  74 
Spans,  124 

Crevices  in  rock,  see  Rock 
Cribs,  26,  33,  in 
Crib  anchor,  33,  134,  135 
Crib  coffer-dam:  see  Coffer-dam 
Current,  strength  of,  120 
Cutting  edges,  So,  122,  147 
Cutting  shoe,  122 

Cutwaters,  10,  18,  26,  66,  129,  130,  131 
Cylinder — 

Bracing  for,  83,  84 
Calking  for,  82 
Guide  for,  81 
Pier,  33,  80,  82,  83,  87 
Piles  for,  83 
Thickness  of,  82,  83,  84 
Damaged — 

Coffer-dam,  24,  32,  35,  60,  66,  76 
Piles,  10 

Danube  river.  9,  40 
Decking  for  coffer-dam,  134 
Defects  in — 

Cement,  114,  136 
Piles,  10 
Stone,  137 

Deposit  in  coffer-dam,  134 
Depositing  concrete  under  water,  see  Con- 
crete 

Derricks,  102,  117 
Derrick,  see  Pile-driver 
Design  of  piers,  see  Piers 
Direct  connected  pump,  97 


154 


INDEX. 


Disposal  of  excavation,  26,  60,  71 
Diver  employed,  31,  36,  76,  87 
Docks,  Victoria,  B.  C.,  77 
Dowels  for  stone,  137 
Drawings  to  show — 

Bridge  location,  120 

Bridge  plan,  120 
Dredger — 

Capacity  of,  101,  102,  103,  135,  148 

Clam-shell,  102 

Claw,  72,  So,  102 

Cost  of,  103,  148 

Derrick  for,  102 

Dipper,  103 

Edward's  Cataract  pump,  101 

Elevator  type,  102 

Engine  for,  78,  148 

Furnished,  134 

Grapple,  102 

Lancaster,  102 

Osgood,  103 

Pump,  78,  99,  101,  148 

Sand-digger,  102 

Scraper,  13 

Seagoing,  101 

Spoon, 13 
Dredging,  10,  15,  80 

Amount  necessary,  16 

Cost  of,  102,  103,  105 

Pumps  for,  78,  99,  101,  148 

Rock,  72 

Soft  bottom,  106 

Wells  for,  80 
Drift  in  sand,  18 

Drift  bolts,  33,  36    38,  39,  57,  60,  71 
Drilling,  test,  see  Boring 
Driver,  see  Pile-driver 
Durability  of  piles,  40,  72 
Earth  bank  coffer-dam,  see  Coffer-dam 
Economic — 

Bridge  cost,  124,  125 

Coffer-dam  construction,  26 

Pier  spacing.  120,  124,  125 
Eddies,  129,  130,  131 
Efficiency  of  pumps,  96,  148,  149 
Ejector  for  priming,  101,  148 
Electricity — 

Blasting  by.  73 

Hoisting  by,  98,  117 

Pumping  by,  97 
Engine,  see  Hoist 
Erection,  steel  coffer-dam,  147 
Estimates,  139,  146 
European  pier  design,  127 
Examination  for  bridge  site,  120 
Excavation    (see    Dredging)  —  7,     10,    60, 
61 

Classification,  135,  145 

Disposal  of,  26,  60,  71,  135 

Measurement,  139 

Rock,  72,  86,  145 

Scraper  for,  13 

Spoon  for,  14 


Experiments — 

Piers,  form  of,  129,  130,  131 

Puddle,  12 

Timber,  wet,  33 
Exterior  puddle,  see  Puddle 
Facing  for  concrete,  72,  in,  114,  143 
Failure  of — 

Coffer-dam,  see  Coffer-dam 

Contractor  to  prosecute  work,  139 

Puddle,  28 
Filling,  see  Puddle 
Floating  coffer-dam,  74 
Footing  course,  4,  117,  127 
Form  of — 

Foundation,  5,  124 

Piers,  129,  130,  131 

Sheet  piles,  50,  51,  52,  53 
Forms  for  concrete,  in,  113,  115,  141,  142, 

144 
Formula  for — 

Cost  of  hoists,  45 

Cylinder  thickness,  84 

Economic  span,  124 

Pile  loads,  49 

Sheet  pile  thickness,  54,  56 

Struts,  56 

Fort  Monroe,  Va.,  64 
Forth  Bridge  piers,  86 
Foundations — 

Ancient,  I,  3.  4,  5,  40 

Care,  increased,  I 

Changes  in,  136 

Character  of,  106,  117,  124,  146 

Coffer-dam,  origin,  3,  5 

Concrete,  see  Concrete 

Crib,  early  type,  5 

Difficult,  very,  120,  124 

Doubt  of  obtaining,  125,  146 

Encaissement,  3 

Footing  course,  4,  117,  127 

Form  of,  5,  124,  146 

Grillage,  20,  24,  60,  67,  71,  72,  106 

Open  caissons,  3,  4,  13 

Origin,  sub-aqueous,  3 

Piles  and  concrete,  3,  106,  no 

Piles,  bearing,  106,  146 

Piles  under  cylinders,  83 

Pneumatic  caisson,  5 

Risk  of,  125 

Rock  bottom,  see  Bottom 

Roman,  I 

Steel  shells,  33,  80,  82,  83,  87 

Sub  aqueous,  3,  77 

Tropical,  i 

Frame  for  coffer-dam    see  Coffer-dam 
Freshet,  damage  by,  66,  76 
Friction  lever,  44 
Frost  on  mortar,  136 
Gate  valve  for  priming,  101 
Girders,  circular,  89,  147 
Government — 

Approval,  120 

Requirements,  120 


INDEX. 


155 


Grades,  135 

Gravel  bed,  see  Bottom 

Gravel  in  puddle,  12,  15,26,  76,  see  Puddle 

Grease  for  leaks,  30,  36 

Grillage  (see  Foundation) — 

Removal,  74 
Guide — 

Cylinder  pier,  81 
Piles,  7,  49,  57,  71 

Pile-driver,  43 

Pipe  for  drilling,  121 
Guide  for  piles,  43,  57 
Gunny  sacks,  26,  28,  33.  36,  64,  76 
Half-tide  coffer-dam,  89 
Hammer,  see  Pile-driver 
Hand- 
Derrick,  40,  41,  43 

Pump,  93 

Harlem  ship-canal  bridge,  36 
Hoist  engine  for — 

Derrick,  117,  149,  150 

Pile-driver,  44,  45,  68,  78,  149,  150 

Scraper,  13 
Hoist- 
Cost  of,  44,  45 

Electric,  98,  117 

Weight  of,  149,  150 
Huron  river,  Mich.,  59 
Hutcheson  bridge,  6 
Ice  protection,  9,  10,  26,  129,  130,  131 
Illinois  &  Miss,  canal,  113 
Illinois  river,  62 
Inspection,  139 
Iron  coffer-dam,  83,  86 
Iron  sheet  piles,  91 
Jet  for  pile-driver,  70 
Kanavvah  river,  W.  Va.,  14,  117 
Kankakee  river,  62 
Karun  river,  Persia,  I 
Key  piles,  57 
Knives  for  drill-rope,  121 
Laitance  of  cement,  109 
Lansdell  siphon,  93 
Largest — 

Arch,  3 

Coffer-dam,  8 
Layers  of  concrete,  109,  113,  138,  143,  144, 

145 
Laying  concrete,  rules  for,   113,   138,  143 

M5 
Leaks  cured  by — 

Asphalt,  65  ' 

Boxing  in,  32,  39,  60 

Calking  joints,  20,  36 

Candle  wicking,  20,  39 

Cane-stalks  crushed,  28 

Canvas  funnel,  32 

Clay  cylinders,  29 

Clay  dams,  89 

Concrete  in  sacks,  66 

Exterior  puddle,  28,  78 

Gravel  and  clay,  26 

Grease,  30,  36 


Leaks  cured  by—  Continued. 

Grouting,  89 

Hot  asphalt,  65 

Manure,  28,  32 

Packing  puddle,  12,  28,  77 

Puddle,  exterior,  28,  78 

Puddling  rock  seams,  25 

Repuddling,  28 

Round  braces,  30,  38 

Sacks,  26,  36,  66,  76 

Sheet  piles,  12,  28 

Stiff  grease,  30,  36 

Stock  ramming,  12,  28,  77 

Straw  and  gravel,  20,  28 

Tarpaulin,  30,  32,  33,  35,  36,  65 

Washers  on  rods,  30 

Water-head,  32,  39 
Ledges,  see  Rock 
Length,  economic  span,  124,  125 
Leveling  course  concrete,  107,  117 
Lift  of  pumps,  96,  100,  148,  149 
Little  Bras  d'Or  river,  Canada,  82 
Location  of — 

Bridge,  120 

Coffer-dam,  86,  87 

Piers,  120 

Pumps,  100 

Manure  for  leaks,  28,  32 
Map  of  bridge  location,  120 
Maslin  pump,  96 
Masonry — 

Ashlar,  136 

Footing  courses,  74,  117 

Laying,  137 

Marking  stones,  74 

Measurement,  139 

Removing,  73,  74 

Rubble,  86,  90 

Specifications  for,  136,  137,  138 
Mass,  sewerage  system,  60,  61 
Mattresses,  4 
Maul  for  driving  pipe,  122 
Maul  as  pile-driver,  40 
Measurement  of  work,  139 
Melan  Arch,  Topeka,  78 
Metal  coffer-dam,  35,  83,  86,  147 
Missouri  river,  127 
Mississippi  river,  20,  32,  67 
Monolithic  concrete,  72,  in,  112,  113,  143 
Morison's  pier  design,  125 
Mortar,  cement,  136,  143.  145 
Movable  coffer-dam,  see  Coffer-dam 
Mud,  see  Bottom 

Nasmyth  hammer,  14,  45,  46,  47    48,  49 
Natural  cement,  in,  136,  143,  145 
Navigable  rivers,  see  River 
Navigation,  needs  of,  120 

Interference  with,  135 
New  York  State  canals,  45,  50 
Nippers,  pile-driver,  43 
Obstruction — 

To  boring.  121 

By  piers,  125 


1 56 


INDEX. 


Ohio  river,  15,  133 

Oil  paper  for  concreting,  142 

Origin  of — 

Coffer-dam,  3,  5 

Foundations,  3 
Packing  puddle,  12,  28,  77 
Painting,  65,  147 
Parnitz  river,  Germany,  72 
Payment,  manner  of,  134 
Pierce  boring  auger,  121 
Piers — 

Architectural  design,  125,  127,  131 

Batter  of,  125 

Bracing  for  cylinders,  83 

Concrete,  72,  in,  143,  144 

Coping  for,  125,  127,  129 

Cost  of,  for  economy,  125 

Cylinder,  33,  80,  82,  83 

Design  of,  125.  127,  129,  130,  131 

Economic  spacing,  120 

European  design,  127 

Experiments  en  form,  129.  130,  131 

Filling  of  concrete,  So,  82,  143 

Forth  bridge,  86 

Hutcheson    6 

Location  of,  120,  125 

Morison's  design,  125 

Obstruction  of,  125,  129,  130,  131 

Pivot,  82 

Relation  to  spans,  i,  124 

Removal,  72,  74 

Starlings  of,  125,  129,  130,  131 

Thickness  of  tubular,  84 

Tubular  steel,  33,  80,  82,  83 
Pile-driver — 

Ancient,  5.  40,  41 

Beetle  for,  40' 

Bull-wheel  for,  41 

Clamps,  43 

Cost  of  outfit,  43,  44 

Cram-Nasmyth,  49 

Derrick,  41/42,  43.  45 

Engine,  44,  45,  78,  149.  150 

Friction  lever,  44 

Guides,  43 

Hammer,  41,  43,  44,  68.  77,  78 

Hand  derrick,  40,  41,  43 

Hoist  engine  for,  44,  45,  68,  78,  149,  150 

Horse-power,  41,  43 

Lidgerwood,  43 

Maul,  40 

Nasmyth,  14,  45,  46,  47,  48,  49 

Nippers,  43 

Rock  drill  used,  14 

Scow  for,  43,  44,  45 

Sheet  pile,  14,  41 

Sledge,  40 

Tongs,  43 

Warrington-Nasmyth,  46,  47 

Water  jet,  70 

Windlass,  40 
Piles- 
Ancient  use,  3,  4,  5,  40 


Piles— Continued. 

Bearing,  106,  146 

Bearing  power,  49,  146 

Blasting  out,  73 

Cost  driving,  48 

Clamps,  43 

Damaged,  10 

Durability  of,  40,  72 

Guide  7,  57,  49,  71 

Guiding,  43 

Key,  57 

Payment  for,  139,  146 

Pointing,  see  Pointing 

Protection,  134 

Pulling,  50,  73 

Pulling  lever,  50 

Pulling  scow,  50 

Rings  for,  70 

Sawing  off,  50,  83,  146 

Sheet  piles,  ancient,  4 
See  sheet  piles 

Shoes,  50,  53 

Specifications  for,  135,  141,  146 

Splitting  of,  43 

Temporary,  135 

Under  cylinders,  83 
Pivot  pier — 

Cylinders  for,  82 

Coffer-dam  for,  20,  36,  38,  39,  147 
Pointing  piles,  24,  50,  51,  53,  57,  60 
Pointing  with  mortar,  136 
Porous  bottom,  16,  28,  141 
Portland  cement,  72,  113,  115,  116,  142 
Potomac  river,  63 
Primers  for  pumps,  100,  101,  148 
Pressure  of — 

Puddle,  54 

Water,  see  Water 
Proportions  for  concrete,  67,  72,  107,  no, 

in,  116,  138,  143,  145 
Protection  of — 

Bank, 4 

Coffer  dam,  26,  33,  134 

From  ice,  see  Ice 
Puddle- 
Blue  clay,  72 

Chamber,  7,  10,  33,  36,  38,  56,66,  72,  74,77 

Clay,  7,  17,  26,  33,  66,  88 

Clay  and  gravel,  12,  15,  26,  76,  134 

Concrete.  39,  78,  87 

Experiments,  12 

Exterior,  17,  20,  25,  26,  28.  33,  63,  66,  71, 
76,  77 

Failure  of,  28 

Pressure  of,  54 

Sacked,  26,  28,  33,  64 
Pulling  piles,  50,  73 
Pulling  test  tubing,  124 
Pulsometer,  30^  32,  90,  94,  95 
Pumping,   15,    17,   18,  25,  30,  32,  39,  61,  63, 
64,  66,  72,  76,  89 

Amount  of,  92 

Electricity  for,  97 


INDEX. 


157 


Pumps — 

Ancient,  92,  93 

Bascule,  92 

Box,  93 

Bucket- wheel,  92 

Capacity,  77,  7§,  93,  94,  99,  101,  135,  148 

Centrifugal,  15,  17,  18,  30,  39,  61,  63,  66, 
77,  78,  90,  96,  97,  98,  99,  100,  148,  149 

Chapelet,  92,  93 

Chattanooga  plant,  99 

Cost  of,  93,  148 

Direct  connected,  97 

Double  suction,  100 

Dredging,  78,  99,  101,  148 

Edward's  cataract,  101 

Efficiency  of,  96 

Ejector  for  priming,  101,  148 

Electric,  97 

Forth  bridge,  99 

Furnished,  134 

Gate  valve  primer.  101 

German  high  test,  97 

Hand,  93 

Heald  &  Sisco,  97,  148 

Lift  of,  96,  100,  148 

Location,  best,  100 

Maslin,  96 

Piston  of  dredging.  101 

Primers,  100,  148 

Pulsometer,  30,  32,  90,  94,  95 

Reciprocating,  96 

Sampling,  121,  122 

Siphon,  93 

Speed  for,  149 

Strainers  for,  98 

Suction  details,  98 

Suction  pipe,  98,  100,  148 

Sump  or  well  for,  60,  99 

Tests  of,  96,  97 

Weight  of,  148 

Wooden,  93 
Quality  of — 

Cement,  114,  136,  142,  145 

Timber,  138,  139,  146 
Quicksand,  67,  135 
Rammer  for  puddle,  28,  77 
Red  river,  U.  S.,  in 
Rejection  of  material,  137,  139 
Removal  of — 

Coffer-dam,  20,  33,  74,  134,  147 

Grillage,  74 

Piers,  72,  74 

Piles,  50,  73 

Test  core,  122 
Republican  river,  Kan.,  20 
Requirements,  War  Dep't,  120 
Rhine  river,  5 
Rings  for  piles,  70 
Rip-rap,  26,  72,  83 
Rivers,  navigable,  120 
River — 

Aa,  Russia,  83 

Arkansas,  20,  70 


River —  Continued. 

Bear,  Can.,  83 

Charles,  Boston,  63,  ITO 

Clyde,  Scotland,  6 

Coosa,  Ala.,  74,  no,  117 

Danube,  9,  40 

Huron,  Mich.,  59 

Illinois,  62 

Kanawah,  W.  Va.,  14,  117 

Kankakee,  111.,  62 

Karun,  Persia,  i 

Little  Bras  d'Or,  82 

Missouri,  127 

Mississippi,  20,  32,  67 

Ohio,  15 

Parnitz,  Germany,  72 

Potomac,  63 

Red,  in 

Republican,  Kan.,  20 

Rhine,  5 

Sault  Ste.  Marie,  28 

Schuylkill,  Pa.,  74 

Scioto,  Ohio,  13 

Soane,  France,  109 

St.  Lawrence,  18 

Tennessee,  66 

Thames,  4,  77 

Western,  U.  S.,  17,  18,  20 
Riveting — 

Boiler,  80,  82,  147 

Water-tight,  80,  82,  147 
Roads,  construction,  3 
Robinson,  coffer-dam,  24 
Rock- 
Bottom,  see  Bottom 

Crevices,  25,  28,  39,  66,  89,  107 

Joint  with  sheet  piles,  72 

Ledges,  86 

Stepping  of,  86,  107 
Rock-drill  pile-driver,  14 
Rod  bracing,  30,  38,  67,  134 
Roman  foundations,  I 
Rubble  masonry,  86,  90 

Rules  laying  concrete,  113,  138,  143,  144,  145 
Sacked  puddle,  see  Puddle 
Sacks  used,  26,  28,  33,  36,  64,  66,  76 
Samples  of  borings,  121,  122 
Sampling  pumps,  121,  122 
Sand  (see  Bottom) — 

For  concrete,  in,  115,  136,  143,  145 

Digger,  102 

Drift  in,  18 

Pump,  121,  122 

Shells  in,  77 

Sault  Ste.  Marie  river,  28 
Sawing  off  piles,  50,  83 
Schuylkill  river,  74 
Scioto  river,  Ohio,  13 
Scow,  pile  pulling,  50 
Scow,  see  Pile-driver 
Scraper,  13 

Sec'y  of  War,  approval,  120 
Setting  time,  concrete,  no,  114,  143,144,  145 


158 


INDEX. 


Sewer  coffer-dam,  60,  61 

Shale,  60 

Sheet  pile  coffer-dam,  see  Coffer-dam 

Sheet  piles — 

Calculations,  54,  56 

Clamps  for,  57 

Close,  135 

Compound,  52,  53,  61,  66 

Driver  for,  14,  41 

Early  use,  4,  6,  7 

Forms  of,  50,  51 

Guides,  57 

Leak  remedy,  12,  28 

Metal,  91 

Old,  72 

Plank,  35,  50,  59,  60,  66,  67,  77,  134 

Pointing,  24,  50,  51,  57,  60 

Rock  joint  with,  72 

Shoes  for,  50,  51,  52 

Slanting,  60,  61 

Square,  8,  10,  24,  51,  60,  77 

Thickness,  53,  54,  56 

Tongue  and  groove,   20,   24,   51,  60,  71, 
76,  77,  78 

V  shape,  20,  51 

Wakefield,    14,   20,   53,  61,  62,  63,  64,  141 
Shells  in  bottom,  77 
Shocks  of  waves,  83,  89 
Shoe  for — 

Piles,  50,  53 

Pipe,  122 

Sheet  piles,  50,  51,  52 
Shoring,  see  Bracing 
Silt  bottom,  33 
Sinking  coffer-dam,  20,  76 
Siphon,  93 
Site  of  bridge,  120 
Site,  examination  of,  120,  124 
Slanting  piles,  60,  61 
Sledge  for  pile-driver,  40 
Sluice,  7,  87 

Soane  river.  France,  109 
Soapstone  bottom,  20 
Sounding  rod,  86 
Soundings,  86,  120,  121 
Spans — 

Cableway,  117,  118 

Economic  formula,  125 

Economic  length,  124,  125 

Length  of,  124 

Relation  to  piers,  I,  124 
Spacing  of  piers,  120,  124,  125 
Spears  for  drill  rope,  121 
Specification  for — 

Coffer-dam,  see  Coffer-dam 

Cement,  see  Cement 

Foundation,  141,  146 

Masonry,  136,  137,  138 

Piles.  135,  141    146 

Steel  coffer-dam,  147 

Timber,  138,  139,  146 
Speed  for  pumps,  149 
Splicing  coffer-dams,  67,  147 


Springs  in  bottom,  32 

Spuds,  75 

Staging  to  locate  pier,  86 

Starlings,  10,  18,  26,  66,  125,  129,  130,  131 

Steel  coffer-dam,  83,  86,  147 

Steel  shells,  So,  82.  83 

St.  Lawrence  river,  18 

Stock  rammer,  12,  28,  77 

Stone — 

Concretes.,  in,  115,  143,  145 

Defects  in,  137 

Dressing,  137 

Protection,  83,  135 

Quality  of,  136 

Rubble,  137 

Samples,  137 

Substitute  for,  So 
Strainer  for  pump,  98 
Struts,  see  Timber 
Suction-pipe,  98,  148 
Sump  for  pump    60,  99 
Suspension  bridge  tower,  8 
Swab,  121 

Swift  water,  see  Water 
Tables  of— 

Pumps,  centrifugal,  148 

Pumps,  dredging,  148 

Pump  speed,  149 

Hoisting  engines,  149,  150 
Tarpaulin  used,  30,  32,  33,  35,  36,  65 
Tennessee  river,  66 
Test  borings,  see  Borings 
Tests  of — 

Cement,  115,  136,  142,  145 

Pumps,  96,  97 
Thames  river,  4,  77 
Thickness  of — 

Cylinders,  84 

Sheet  piles,  53,  54,  56 
Tide  coffer-dam,  8,  53,  63,  86,  89 
Tide,  see  Water 
Timber — 

Casing,  5 

Framing,  135 

Piles,  see  Piles 
see  sheet  piles 

Price  for,  139,  146 

Scarcity  of,  79 

Specifications,  138,  139,  146 

Struts,  7,  30,  33,  33,  39,  5^,  64 

Water-soaked,  33 
Tongs- 
Pebble,  124 

Pile-driver,  43 

Tongue  and  groove,  see  Sheet  piles 
Tools  furnished,  134 
Topeka  coffer  dam,  78 
Trezzo  arch,  i 
Tripod  for  test  boring,  121 
Tube  for — 

Concreting,  108,  no 

Drilling,  121 

Pier,  33,  80,  82,  83,  87 


INDEX. 


59 


Van  Duzen  jet,  93 
Velocity  of  water,  129,  130,  131 
Victoria,  B.  C.,  docks,  77 
Voids  in  masonry.  136 
V  shape  pile  joint,  20,  51 
Wakefield  sheet  piles,  see  Sheet  piles 
Wales- 
Calculation  of,  56 

Ordinary,  7,  35,  59,  134 
War  Dep't  requirements,  120 
Washers  for  leaks,  30 
Water— 

For  concrete,  113,  114,  143 

Deep,  8,  10,  63 

Eddies,  129,  130,  131 

High,  118,  119,  120 

Jet,  70 

Low,  120 

Pressure,     20,     25,     28,    32,    35,    54,    85, 


Water — Continued. 

Shallow,  i,  5,  13 

Shock  of  waves,  83,  89 

Soaked  timber,  33 

Swift,  10,  26,  32,  107 

Tide,  8,  86 

Velocity,  129,  130,  131 
Water-tight  compartments,  76 
Water-tight  riveting,  So,  82,  147 
Waterway,  120,  129 
Weight  of — 

Hoist  engines,  149,  150 

Pumps,  148 
Well  driller,  121 
Well  for  pump,  60,  99 
Wells  in  concrete,  114 
Wellington  pile  formula,  49 
Western,  U.  S.,  rivers,  17,  18,  20 
Windlass  pile-driver,  40 
Wooden  pump,  93 


Wakefield  Triple=lap  Sheet  Piling, 


This  sheeting  matches  perfectly ;  can  be  made  as  wanted 
at  the  work,  of  any  available  sound  lumber.;  stands  driving 
without  an  equal,  and  stops  water  absolutely  at  such  trifling 
cost  that  it  invariably  proves  satisfactory. 


PATENTED. 


Royalty  charge,  25  cents  per  foot,  of  completed  work  ; 
i.e. ,  a  coffer-dam  25'  X  50',  sheeted  on  four  sides,  amounts  to 
150'  @  25c.  —  $37.50. 

USED  BY  ARMY  ENGINEERS,  RAILWAY  ENGINEERS, 
CITY  ENGINEERS,  CONTRACTORS,  ETC, 


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8 


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9 


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11 


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12 


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13 


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15 


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